CN106685863B

CN106685863B - Apparatus and method in a wireless communication system

Info

Publication number: CN106685863B
Application number: CN201510745034.8A
Authority: CN
Inventors: 陈晋辉; 郭欣; 孙晨
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2015-11-05
Filing date: 2015-11-05
Publication date: 2021-02-26
Anticipated expiration: 2035-11-05
Also published as: CN106685863A; KR20190028814A; BR112017021210A2; CN107493246A; WO2017076354A1; US11489570B2; US10778302B2; JP6388083B2; KR20180063322A; US20180076866A1; CN107493246B; CN113037343A; EP3373535A4; US20190190576A1; US10205501B2; KR102380060B1; EP3930273A1; JP2018513588A; US20200373980A1; EP3373535B1

Abstract

Apparatus and methods in a wireless communication system are disclosed. An apparatus at a base station side in a wireless communication system for multi-user superposition transmission, comprising: a superposition control unit, which inserts a demodulation reference signal corresponding to the data stream in the data stream of each user equipment in a group of user equipments including a plurality of user equipments and superposes the demodulation reference signals corresponding to the data streams of the user equipments, and allocates specific transmission power to the data streams of the user equipments so that the data streams of the user equipments are transmitted to the user equipments with the same time-frequency resources without using MIMO performance gain and/or code division multiplexing; and the indication generating unit is used for generating an indication of a demodulation reference signal corresponding to the data stream of other user equipment for at least the first user equipment so as to assist the first user equipment in demodulating the data of the multi-user superposition transmission. Thus, signaling overhead can be reduced, and channel estimation accuracy can be improved.

Description

Apparatus and method in a wireless communication system

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to an apparatus and method for a base station side and an apparatus and method for a User equipment side in a wireless communication system for Multi-User super position Transmission (MUST).

Background

In the existing 3GPP, the base station inserts the demodulation reference signal into the data stream of the user equipment and notifies the user equipment, and the transmission power of the user data stream is the same as that of the user reference demodulation signal. Note that in some examples, the demodulation reference signal may also be referred to as a user-specific reference signal, and the data stream may also be referred to as a data layer. In multi-user superposition transmission, the existing demodulation reference signal transmission mode has the following defects: 1) the base station needs to inform at least one user equipment of the power distribution coefficient, and the dynamic power distribution coefficient notification needs to occupy more signaling overhead as the power distribution coefficient can be dynamically adjusted according to the channel condition; and 2) the transmission power allocated to the demodulation reference signal of each user equipment is only partial power, which affects the quality of equivalent channel estimation.

Disclosure of Invention

The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. However, it should be understood that this summary is not an exhaustive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

In view of the above problems, it is an object of the present disclosure to provide an apparatus and method at a base station side and an apparatus and method at a user equipment side in a wireless communication system for multi-user superposition transmission, which can overcome the drawbacks of the above prior art, respectively, avoid large signaling overhead due to notification of power allocation coefficients and enable demodulation reference signals to be transmitted at full power to improve channel estimation quality.

According to an aspect of the present disclosure, there is provided an apparatus on a base station side in a wireless communication system for multi-user superposition transmission, the apparatus comprising: a superposition control unit configured to insert a demodulation reference signal corresponding to a data stream in each data stream of a group of user equipments including a plurality of user equipments and superpose the demodulation reference signals corresponding to the data streams of the user equipments, wherein the superposition control unit allocates a specific transmission power to the data stream of the user equipments so that the data stream of the user equipments is transmitted to the user equipments with the same time-frequency resources without using mimo performance gain and/or code division multiplexing; and an indication generating unit configured to generate, for at least a first user equipment of the plurality of user equipments, an indication of demodulation reference signals corresponding to data streams of other user equipments of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission.

According to a preferred embodiment of the present disclosure, the demodulation reference signals corresponding to the data streams of the respective user equipments have different orthogonal codes, so that the demodulation reference signals corresponding to the data streams of the respective user equipments are transmitted to the respective user equipments on the same resource element.

According to another preferred embodiment of the present disclosure, each user equipment has only a single-layer data stream, and the superposition control unit inserts demodulation reference signals supporting only the single-layer data stream into the data streams of each user equipment, respectively.

According to another preferred embodiment of the present disclosure, the superposition control unit is further configured to allocate a specific transmission power to the demodulation reference signals corresponding to the data streams of the respective user equipments, and superpose the demodulation reference signals corresponding to the data streams of the respective user equipments according to the allocated power.

According to another preferred embodiment of the present disclosure, the demodulation reference signals corresponding to the data streams of the respective user equipments are superimposed in a different manner from the data streams of the respective user equipments.

According to another preferred embodiment of the present disclosure, the transmission power allocated to the demodulation reference signal corresponding to the data stream of each user equipment is the same as the transmission power allocated to the data stream.

According to another preferred embodiment of the present disclosure, the above indication is included in physical layer signaling.

According to another preferred embodiment of the present disclosure, the superposition control unit is further configured to determine a group of reference signals for a group of user equipments from a plurality of groups of reference signals respectively constituted by a plurality of demodulation reference signals, wherein the determined group of reference signals comprises a number of demodulation reference signals greater than or equal to a number of user equipments comprised by the group of user equipments, and the indication comprises an index with respect to the determined group of reference signals.

According to another preferred embodiment of the present disclosure, the indication further includes information of a demodulation reference signal for the first user equipment in the determined reference signal group.

According to another preferred embodiment of the present disclosure, the indication further includes at least one bit for indicating to the ue an indication manner regarding the demodulation reference signal, where the indication manner includes a demodulation reference signal group indication manner and a conventional demodulation reference signal indication manner.

According to another preferred embodiment of the present disclosure, the indication generating unit is further configured to use a legacy demodulation reference signal indication approach for at least a second user equipment in the group of user equipments.

According to another preferred embodiment of the present disclosure, the above apparatus further comprises: a storage unit configured to store information of a demodulation reference signal group set including a plurality of reference signal groups, wherein a plurality of demodulation reference signals included in each demodulation reference signal group are code-division orthogonal to each other, and a superposition control unit reads the storage unit to determine the reference signal group for a group of user equipments.

According to another preferred embodiment of the present disclosure, the above apparatus is a base station, and the apparatus further includes: a transmitting unit configured to transmit the superimposed demodulation reference signal and indication to at least the first user equipment.

According to another aspect of the present disclosure, there is also provided an apparatus on a base station side in a wireless communication system for multi-user superposition transmission, the apparatus comprising: an insertion control unit configured to insert a common demodulation reference signal in the superimposed data streams of the plurality of user equipments; and an indication generating unit configured to generate, for at least a first user equipment of the plurality of user equipments, an indication of power allocation coefficients corresponding to data streams of respective ones of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission.

According to another aspect of the present disclosure, there is also provided an apparatus on a user equipment side in a wireless communication system for multi-user superposition transmission, the apparatus comprising: an equivalent channel estimation unit configured to estimate an equivalent channel corresponding to a data stream of the user equipment and an equivalent channel corresponding to a data stream of other user equipment according to an indication from a base station about a demodulation reference signal of the user equipment and a demodulation reference signal of the other user equipment after superposition, wherein the demodulation reference signal of the user equipment and the demodulation reference signal of the other user equipment are respectively inserted into the data stream of each user equipment, and the data streams of each user equipment are transmitted by the base station at a specific transmission power and the same time-frequency resource without using multiple-input multiple-output performance gain and/or code division multiplexing; and a data demodulation unit configured to demodulate data of the multi-user superposition transmission according to the estimated equivalent channel.

According to another aspect of the present disclosure, there is also provided an apparatus on a user equipment side in a wireless communication system for multi-user superposition transmission, the apparatus comprising: an equivalent channel estimation unit configured to estimate an equivalent channel corresponding to a superimposed data stream from the base station according to a common demodulation reference signal from the base station, wherein the common demodulation reference signal is inserted in the superimposed data stream; and a data demodulation unit configured to demodulate data of the multi-user superposition transmission according to the estimated equivalent channel and an indication from the base station about power distribution coefficients of the user equipment and other user equipments.

According to another aspect of the present disclosure, there is also provided a method at a base station side in a wireless communication system for multi-user superposition transmission, the method comprising: inserting a demodulation reference signal corresponding to a data stream into the data stream of each user equipment in a group of user equipment comprising a plurality of user equipments respectively and superposing the demodulation reference signals corresponding to the data streams of the user equipments respectively, wherein the data streams of the user equipments are allocated with specific transmission power so that the data streams of the user equipments are transmitted to the user equipments with the same time-frequency resources without utilizing MIMO performance gain and/or code division multiplexing; and generating, for at least a first user equipment of the plurality of user equipments, an indication of demodulation reference signals corresponding to data streams of other user equipments of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission.

According to another aspect of the present disclosure, there is also provided a method at a base station side in a wireless communication system for multi-user superposition transmission, the method comprising: inserting a common demodulation reference signal into the superposed data streams of the plurality of user equipment; and generating, for at least a first user equipment of the plurality of user equipments, an indication of power allocation coefficients corresponding to data streams for respective ones of the plurality of user equipments to assist the first user equipment in demodulating data for the multi-user superposition transmission.

According to another aspect of the present disclosure, there is also provided a method at a user equipment side in a wireless communication system for multi-user superposition transmission, the method comprising: estimating an equivalent channel corresponding to a data stream of the user equipment and an equivalent channel corresponding to a data stream of other user equipment according to an indication from a base station about a demodulation reference signal of the user equipment and a demodulation reference signal of the other user equipment after superposition, wherein the demodulation reference signal of the user equipment and the demodulation reference signal of the other user equipment are respectively inserted into the data stream of each user equipment, and the data stream of each user equipment is transmitted by the base station at a specific transmission power and with the same time-frequency resource without utilizing multiple-input multiple-output performance gain and/or code division multiplexing; and demodulating data of the multi-user superposition transmission according to the estimated equivalent channel.

According to another aspect of the present disclosure, there is also provided a method at a user equipment side in a wireless communication system for multi-user superposition transmission, the method comprising: estimating an equivalent channel corresponding to the superposed data stream from the base station according to a common demodulation reference signal from the base station, wherein the common demodulation reference signal is inserted into the superposed data stream; and demodulating data of the multi-user superposition transmission according to the estimated equivalent channel and an indication from the base station about power distribution coefficients of the user equipment and other user equipments.

According to another aspect of the present disclosure, there is also provided an electronic device, which may include a transceiver and one or more processors, which may be configured to perform the functions of the method or the corresponding units in the wireless communication system according to the present disclosure described above.

According to other aspects of the present disclosure, there are also provided computer program code and a computer program product for implementing the above-described method according to the present disclosure, and a computer readable storage medium having recorded thereon the computer program code for implementing the above-described method according to the present disclosure.

According to the embodiments of the present disclosure, compared to a method of inserting a corresponding demodulation reference signal in a user data stream to obtain a corresponding equivalent channel in the prior art, signaling overhead can be reduced by performing superposition transmission on demodulation reference signals of multiple users, and more accurate channel estimation can be obtained by inserting a common demodulation reference signal in a data stream after superposition of multiple users.

Additional aspects of the disclosed embodiments are set forth in the description section that follows, wherein the detailed description is presented to fully disclose the preferred embodiments of the disclosed embodiments without imposing limitations thereon.

Drawings

The disclosure may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which like or similar reference numerals are used throughout the figures to designate like or similar components. The accompanying drawings, which are incorporated in and form a part of the specification, further illustrate preferred embodiments of the present disclosure and explain the principles and advantages of the present disclosure, are incorporated in and form a part of the specification. Wherein:

fig. 1A is a diagram illustrating a first example manner of demodulation reference signal transmission in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure;

fig. 1B is a diagram illustrating a second example manner of demodulation reference signal transmission in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure;

fig. 2 is a block diagram showing a functional configuration example of an apparatus on the base station side in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure;

fig. 3A is a schematic diagram illustrating an example of demodulation reference signal transmission in the case of a non-linear superposition manner according to an embodiment of the present disclosure;

fig. 3B is a schematic diagram illustrating an example of a gray constellation in the case of a non-linear superposition approach according to an embodiment of the present disclosure;

fig. 4A is a schematic diagram illustrating a first example of a demodulation reference signal group indication manner according to an embodiment of the present disclosure;

fig. 4B is a diagram illustrating a second example of a demodulation reference signal group indication manner according to an embodiment of the present disclosure;

fig. 5A is a diagram illustrating an example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the technique of the present disclosure is applied in a case where there are a plurality of groups of user equipments to be subjected to multi-user superposition transmission and each user equipment has a single-layer data stream;

fig. 5B is a diagram illustrating a first example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the techniques of the present disclosure are applied in a case where a user equipment has a multi-layer data stream;

fig. 5C is a diagram illustrating a second example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the techniques of the present disclosure are applied in a case where a user equipment has a multi-layer data stream;

fig. 6 is a block diagram showing a functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure;

fig. 7 is a block diagram showing another functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to the first embodiment of the present disclosure;

fig. 8 is a block diagram showing still another functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to the first embodiment of the present disclosure;

fig. 9 is a flowchart illustrating a signaling interaction procedure in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure;

fig. 10 is a block diagram showing a functional configuration example of an apparatus on the base station side in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure;

fig. 11 is a block diagram showing a functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure;

fig. 12 is a flowchart illustrating a signaling interaction procedure in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure;

fig. 13 is a flowchart illustrating a process example of a method at a base station side in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure;

fig. 14 is a flowchart illustrating a process example of a method on the base station side in a wireless communication system for multi-user superposition transmission according to another embodiment of the present disclosure;

fig. 15 is a flowchart illustrating a process example of a method on a user equipment side in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure;

fig. 16 is a flowchart illustrating a process example of a method at a user equipment side in a wireless communication system for multi-user superposition transmission according to another embodiment of the present disclosure;

fig. 17 is a block diagram of an example structure of a personal computer as an information processing apparatus employable in the embodiments of the present disclosure;

fig. 18 is a block diagram illustrating a first example of a schematic configuration of an evolved node (eNB) to which the techniques of this disclosure may be applied;

fig. 19 is a block diagram illustrating a second example of a schematic configuration of an eNB to which the techniques of this disclosure may be applied;

fig. 20 is a block diagram showing an example of a schematic configuration of a smartphone to which the technique of the present disclosure can be applied; and

fig. 21 is a block diagram showing an example of a schematic configuration of a car navigation device to which the technique of the present disclosure can be applied.

Detailed Description

Exemplary embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings. In the interest of clarity and conciseness, not all features of an actual implementation are described in the specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

Here, it should be further noted that, in order to avoid obscuring the present disclosure with unnecessary details, only the device structures and/or processing steps closely related to the scheme according to the present disclosure are shown in the drawings, and other details not so relevant to the present disclosure are omitted.

Next, an embodiment of the present disclosure will be described with reference to fig. 1A to 21.

Before specifically describing embodiments of the present disclosure, a brief description will be given of contents regarding a Superposition Coding (superpositioning Coding) technique on which a multiuser Superposition transmission is based according to the present disclosure.

By means of superposition coding, a transmitter can communicate with multiple receivers using the same transmission resources. For example, current downlink multi-user superposition transmission can support a base station to simultaneously transmit multiple data streams to more than one user equipment without using different time, frequency, codeword or multi-antenna techniques for differentiation. As an example, consider a radio transmitter Tx communicating with a first receiver Rx1 via a first physical communication link L1 and a radio transmitter Tx communicating with a second receiver Rx2 via a second communication link L2. It is assumed that the radio conditions are weaker for a first receiver/link (e.g., located farther from the transmitting end) and stronger for a second receiver/link (e.g., located closer to the transmitting end) (which may be temporary because radio conditions are constantly changing, especially for mobile stations). In other words, for a fixed transmitted radio power, the signal to interference plus noise ratio SINR and the carrier to interference plus C/I ratio of the first receiver are lower (or much lower) than the corresponding SINR and C/I ratio of the second transmitter. A transmitter Tx, knowing the relative radio conditions of the two receivers, may allocate its power budget proportionally between the two receivers for a particular time slot and a particular carrier frequency, so that a first data block intended for a first receiver Rx1 (receiver in weaker radio conditions) is transmitted with higher power than a second data block intended for a second receiver Rx2 (receiver in stronger radio conditions). For example, given current radio conditions and additional interference due to transmission of a second data block to the second receiver Rx2, the transmitter Tx may use sufficient power for a first data block intended for the first receiver Rx1 to allow the first receiver Rx1 to decode such a block. The transmitter Tx may then use less power for the second data block intended for the second receiver Rx2, but still sufficient for the second receiver Rx2 to decode the second data block using interference cancellation to cancel or reduce the interference caused by the transmission of the first data block. The transmitter Tx then transmits both data blocks on the same carrier frequency and at the same time. Thus, the two data blocks may be considered to be "collided". Because the first data block is transmitted with a higher power allocation than the second data block, the second data block only appears to the first receiver Rx1 as an increase in noise or interference. If the power offset between the transmission of these two data blocks is high enough, the SINR degradation at the first receiver Rx1 may be small and even insignificant. Thus, the first receiver Rx1 should be able to decode the first data block if it is transmitted with sufficient power relative to the transmission rate of the first data block, the current radio conditions and the additional interference caused by the transmission of the second data block. The second receiver Rx2 should also be able to decode the first data block because the second receiver Rx2 receives the first data block with a better SINR than the first receiver Rx1 due to the stronger radio conditions of the second receiver Rx 2. Once the first data block is decoded by the second receiver Rx2, the second receiver Rx2 may process it as interference and cancel the interference from the overall signal received during the period of receiving the two data blocks using known interference cancellation techniques. The residual signal represents the second data block combined with noise and interference originating from other sources. If the second data block is transmitted with sufficient power (but with lower power than the first data block) relative to its transmission rate and the radio conditions of the second receiver Rx2, the second receiver Rx2 should be able to decode the second data block.

Note that this method can be extended to three or more receivers. For example, a maximum power allocation may be used for transmissions to receivers in the weakest radio conditions, a minimum power allocation may be used for transmissions to receivers in the strongest radio conditions, and an intermediate power allocation may be used for receivers in intermediate radio conditions. The receiver in the strongest radio condition may then decode the data block intended for the receiver in the weakest radio condition, cancel the decoded block from the received signal, decode the data block intended for the receiver in the intermediate radio condition, cancel the second decoded block, and finally decode the data block intended for itself (this decoding/cancellation process may be referred to as progressive interference cancellation). A receiver in intermediate radio conditions may also decode a data block intended for a receiver in the weakest radio conditions, cancel it from the received signal, and then decode a data block intended for itself. The receiver in the weakest radio conditions may be able to directly decode the data block intended for it, since this data block is transmitted at the highest power level. It should be understood that one skilled in the art should be able to extend the progressive interference cancellation technique to four or more receivers without additional experimentation or further inventive labor. The receiver may be a mobile station, e.g. a user equipment, and the transmitter may be a base transceiver station, e.g. an eNB, and the data blocks are e.g. data packets, Transport blocks (Transport blocks).

Therefore, the base station can realize multi-user superposition transmission to a plurality of user equipment with larger channel condition difference by using the same transmission resource through linear superposition of signals with different powers. In addition, the base station may also use a non-linear superposition manner of the constellation map partial mapping to implement multi-user superposition transmission to multiple user equipments with larger channel condition difference by using the same transmission resource, and in some embodiments of non-linear superposition, the power allocated to the data streams of the respective user equipments may also be exactly the same. With the development of superposition coding technology, the inventor of the present disclosure considers that when it is applied to an actual communication system, it needs to involve the overhead problem of dynamic indication of transmission power level to the user equipment by the base station, and in order to assist the user equipment in demodulating data signals, the base station usually inserts demodulation reference signals into data, so that there are also the problems of insertion of demodulation reference signals and power allocation manner.

In the present disclosure, two methods of transmitting a demodulation reference signal in a wireless communication system for multi-user superposition transmission are mainly proposed. One is to insert respective demodulation reference signals into data streams of respective users and perform superposition transmission on the demodulation reference signals by allocating certain power to the demodulation reference signals, and the other is to insert a common demodulation reference signal into superimposed data streams of a plurality of users and allocate full power to the common demodulation reference signal for transmission.

Fig. 1A and 1B illustrate the above two demodulation reference signal transmission methods, respectively. Fig. 1A is a schematic diagram illustrating a first example manner of demodulation reference signal transmission in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure, and fig. 1B is a schematic diagram illustrating a second example manner of demodulation reference signal transmission in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure.

Assuming that multi-user superposition transmission is to be performed for user equipment 1 and user equipment 2, and transmission data for user equipment 1 and user equipment 2 are TB1 (transport block 1) and TB2 (transport block 2), respectively, for the first method described above, as shown in fig. 1A, a demodulation reference signal DMRS1 is inserted in the modulated data stream of user equipment 1 and a demodulation reference signal DMRS2 is inserted in the modulated data stream of user equipment 2, respectively, before the power allocation module, so that DMRS1 and DMRS2 are superposed after power allocation is performed, and the superposed demodulation reference signals are transmitted to user equipment 1 and user equipment 2. With the second method described above, as shown in fig. 1B, a common demodulation reference signal DMRS is inserted into the superimposed data streams of the user equipment 1 and the user equipment 2 and full power is allocated to the common demodulation reference signal DMRS, thereby being transmitted to the user equipment 1 and the user equipment 2. It should be noted that in the examples shown in fig. 1A and 1B, the precoding module therein may be omitted, and for the precoded signal streams to be transmitted to the user equipment 1 and the user equipment 2, it may be transmitted to the user equipment 1 and the user equipment 2 through different antennas or also through the same antenna.

The concept according to the technology of the present disclosure is roughly described above with reference to only schematic diagrams of fig. 1A and 1B, and the above-described two demodulation reference signal transmission methods will be described in detail below in the first embodiment and the second embodiment, respectively.

First embodiment

First, a functional configuration example of an apparatus on the base station side in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure will be described with reference to fig. 2. Fig. 2 is a block diagram showing a functional configuration example of an apparatus on the base station side in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure.

As shown in fig. 2, the apparatus 200 according to this embodiment may include a superimposition control unit 202 and an instruction generation unit 204.

The superposition control unit 202 may be configured to insert a demodulation reference signal corresponding to a data stream in the data stream of each user equipment in a group of user equipments including a plurality of user equipments, and superpose the demodulation reference signals corresponding to the data streams of the respective user equipments, wherein the superposition control unit 202 allocates a specific transmission power to the data streams of the respective user equipments so that the data streams of the respective user equipments are transmitted to the plurality of user equipments with the same time-frequency resources without using mimo performance gain and/or code division multiplexing. The specific transmission power allocated to the data stream may be determined according to an existing multi-user linear superposition scheme or a multi-user nonlinear superposition scheme, which is not described herein in detail.

It should be understood that, in the example of the present invention applied to the LTE system, since the LTE system performs Resource scheduling for data transmission according to Physical Resource Blocks (PRBs), the time-frequency Resource may refer to a Physical Resource Block, but may also refer to Resource units such as the same timeslot on the same carrier in other wireless communication systems, which is not limited in this disclosure.

It should be noted that the demodulation reference signals of multiple ues to perform multi-user superposition transmission may be located on the same time frequency Element, for example, Resource Element (RE), or may also be located on different time frequency elements within the same Resource block, so that when the demodulation reference signals of multiple ues are superposed, the superposition of the same Resource Element may be performed, or the superposition of different Resource elements within the same Resource block may also be performed.

For the latter case, that is, the demodulation reference signals of multiple ues are located on different time-frequency units, e.g., resource elements, within the same resource block, although this may provide more available demodulation reference signal resources, other signals (e.g., data streams) of other ues besides the demodulation reference signals may interfere with the channel estimation based on the demodulation reference signals.

In view of the above, as a preferred example, the demodulation reference signals corresponding to the data streams of the respective user equipments have different orthogonal codes, so that the demodulation reference signals corresponding to the data streams of the respective user equipments are transmitted to the respective user equipments on the same resource element or the same reference symbol (reference symbol). The demodulation reference signals of the user equipments use, for example, the same reference signal sequence.

The orthogonal code here may be, for example, an orthogonal code mask (OCC), so that by allocating different orthogonal code masks and transmission powers to the demodulation reference signals of each user equipment, interference of data of other user equipment to the demodulation reference signals can be avoided (each user equipment transmits the demodulation reference signals on the same resource element, so that there is no situation of multiplexing resources of data and the demodulation reference signals), orthogonality between the demodulation reference signals of different user equipment is also ensured by different orthogonal code masks, interference between the demodulation reference signals is avoided, and thus more accurate channel estimation and demodulation can be achieved.

Preferably, the superposition control unit 202 may be further configured to allocate a specific transmission power to the demodulation reference signals corresponding to the data streams of the respective user equipments, and to superpose the demodulation reference signals corresponding to the data streams of the respective user equipments according to the allocated power.

As a preferred example, the data streams of the user equipments are superimposed in a manner different from that of the data streams of the user equipments, for example, the data streams may be superimposed in a nonlinear manner, and the corresponding demodulation reference signals may be superimposed in a linear manner, so that the design flexibility of the demodulation reference signals may be higher, and the processing of the receiver in performing channel estimation may be simpler. Alternatively, however, the manner of superimposing the demodulation reference signals corresponding to the data streams of the respective user equipments may also be the same as the manner of superimposing the data streams of the respective user equipments, i.e., when the data streams are superimposed in a nonlinear manner, the corresponding demodulation reference signals may also be superimposed in a nonlinear manner.

Specifically, in the case that the demodulation reference signals are in a linear superposition manner, different powers are allocated to the demodulation reference signals corresponding to the bit streams of different user equipments (for example, a larger transmission power is allocated to a user equipment farther away from the base station, and a smaller transmission power is allocated to a user equipment closer to the base station/having a better channel condition) to perform linear superposition. Specifically, for the user equipment 1, it is assumed that its demodulation reference signal is s₁And has a power distribution coefficient of alpha₁For the user equipment 2, it is assumed that its demodulation parametersThe test signal is s₂And has a power distribution coefficient of alpha₂The demodulation reference signal s is then weighted by the power distribution coefficient₁And s₂Performing linear superposition to obtain a demodulation reference signal after linear superposition

In the case that the data stream is in a non-linear superposition manner, as shown in fig. 3A, different from the linear superposition manner, bit streams of different users are interspersed and mixed into one bit stream, and the bit stream is jointly modulated based on one gray constellation (as shown in fig. 3B), where different bits correspond to different user bit streams. For example, in the example shown in fig. 3B, the first two bits may represent bitstreams corresponding to long-range user devices and the last two bits may represent bitstreams corresponding to short-range user devices. Of course, the manner shown in fig. 3B is only an example, and those skilled in the art can also specify the user bit stream represented by the corresponding bit according to actual needs.

The linear superposition method has a better interference elimination effect, while the nonlinear superposition method can simplify the design of the receiver, so that a person skilled in the art can select an appropriate superposition method according to actual needs, which is not limited by the present disclosure.

Preferably, in this embodiment, as described with reference to fig. 1A, since the demodulation reference signal of each user equipment is inserted into its data stream before power allocation, the transmission power of the demodulation reference signal allocated to that user equipment is the same as the transmission power of the data stream allocated to that user equipment.

The indication generating unit 204 may be configured to generate, for at least a first user equipment of the plurality of user equipments, an indication of demodulation reference signals corresponding to data streams of other user equipments of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission.

It should be noted that, for the ue farthest from the base station, since the allocated transmit power is the largest, the ue can demodulate its own data stream based on its own demodulation reference signal only, and does not need to know the demodulation reference signals of other ues performing multi-user superposition transmission, and such ue can also be implemented by a legacy ue. For the ue closer to the base station, if the ue needs to know the demodulation reference signal information of the ues farther from the base station in addition to its own demodulation reference signal, even if different precoding or transmission schemes are used for the ues performing multi-user superposition transmission, the ue can deduce its own data stream without specific power allocation information by demodulating the data stream of the other remote ues first and eliminating it as linear interference. That is, in the multi-user superposition transmission, for the demodulation reference signals of the respective user equipments, at least the demodulation reference signal information of the user equipment farther from the base station should be notified to the user equipment closer to the base station.

The "first user equipment" described above is, for example, user equipment closer to the base station. That is, instead of notifying only the first user equipment of its own demodulation reference signal and the corresponding power allocation coefficient as in the prior art, in the technique of the present disclosure, for the first user equipment, the indication generating unit 204 may generate an indication about the demodulation reference signals of the first user equipment itself and the other user equipments to notify the first user equipment of the demodulation reference signals for the first user equipment and the other user equipments to assist the first user equipment in demodulating data of multi-user superposition transmission. It can be understood that, compared with the power allocation coefficient which is dynamically changed and has a fine quantization granularity, the demodulation reference signals allocated to each user equipment are relatively fixed and the user equipment can calculate the power allocation coefficient based on the channel estimation result obtained according to the demodulation reference signals of other user equipment, so that the signaling overhead can be greatly saved.

There are two ways to determine the group index and the composition of the demodulation reference signal group for a group of user equipments to be subjected to multi-user superposition transmission, and usually it is necessary to agree in advance on the base station side and the user equipment side.

The first method is a static method, in which the composition and group index of the reference signal group are predefined in the communication protocol, so that there is fixed storage information about the composition and group index of the reference signal group in both the chips on the base station side and the user equipment side, and the base station only needs to notify the user equipment of the determined index of the reference signal group. Specifically, the superposition control unit 202 may determine a reference signal group for a group of user equipments from a plurality of reference signal groups respectively composed of a plurality of demodulation reference signals, wherein the number of demodulation reference signals included in the determined reference signal group is greater than or equal to the number of user equipments included in the group of user equipments, and the above indication further includes an index for the determined reference signal group.

The second method is a semi-static method, that is, the base station side semi-statically determines the reference signal group for each group of user equipments, and notifies the user equipments through a broadcast method or RRC signaling when the reference signal group changes.

The indication may be included in physical layer signaling, for example, Downlink Control Information (DCI) transmitted through a Physical Downlink Control Channel (PDCCH) in the LTE system, and specifically, scheduling assignment (scheduling assignment) signaling in the DCI may be indicated to the user equipment together with transmission resource scheduling information, and high flexibility of demodulation reference signal configuration and notification may be achieved. Alternatively, the indication may also be included in higher layer signaling (e.g., Radio Resource Control (RRC) signaling) or may also be included in Medium Access Control (MAC) layer signaling, which is not limited by the present disclosure.

Preferably, the indication may further include information of a demodulation reference signal for the first user equipment in the determined reference signal group. The information may be a sequence number of the demodulation reference signal for the first user equipment in the reference signal group, or may also be orthogonal code (OCC) information, so that the first user equipment may know the demodulation reference signals for the remaining other user equipments according to the group index of the received reference signal group and in combination with the demodulation reference signals for itself.

In addition, preferably, the indication may further include at least one bit for indicating to the ue an indication manner regarding the demodulation reference signal, where the indication manner may include a demodulation reference signal group indication manner and a conventional demodulation reference signal indication manner.

The conventional demodulation reference signal indication manner is that a base station indicates its own demodulation reference signal only to a user equipment. For example, the base station may add the legacy user equipment to the multi-user superposition transmission group (e.g., the legacy user equipment is the user equipment in the group farthest from the base station, and therefore uses the maximum transmission power), and the legacy user equipment only needs to demodulate according to its own demodulation reference signal without stripping the data streams of other user equipments. Preferably, the indication generating unit 204 may be further configured to use a legacy demodulation reference signal indication manner for at least a second user equipment (e.g. a legacy user equipment farthest from the base station) in the group of user equipments. And as to the demodulation reference signal group indication manner, its implementation will be described in detail later. In a preferred example, the base station only uses the DMRS group indication method for the short-distance user equipment so as to reduce the system complexity.

It can be understood that, according to the demodulation reference signal indication manner notified by the base station, for a user equipment using the conventional demodulation reference signal indication manner, it can directly demodulate its own data without performing other processing, that is, for such user equipment, it does not need to know that it is performing multi-user superposition transmission, and only needs to demodulate data according to the conventional manner. For the ue using the demodulation reference signal group indication method, the data transmitted by the multiuser superposition needs to be demodulated in a manner described later, that is, the data of the ue with the maximum transmission power is demodulated first, and then the data of the ue itself is demodulated in a nonlinear interference cancellation manner, or the data demodulation can be performed by recovering the constellation diagram. Preferably, for the user equipment to use the demodulation reference signal group indication mode, the demodulation reference signals supporting only a single-layer data stream can be selected.

An example of the demodulation reference signal group indication manner will be described in detail below with reference to fig. 4A and 4B.

Before describing the manner of indicating the demodulation reference signal set in detail, the design principles of the demodulation reference signal set and the demodulation reference signal set are briefly described: the position of the demodulation reference signal group corresponding to each user equipment in the demodulation reference signal group is called a user layer. The design principle of the demodulation reference signal group set composed of a plurality of demodulation reference signal groups is layer-by-layer design, that is, all possible demodulation reference signals are found to be the constituent elements of the demodulation reference signals of the first user layer, then, for the demodulation reference signal composition of the first user layer, the demodulation reference signals orthogonal to the demodulation reference signals for the constituent elements of the first user layer are found to be the demodulation reference signals of the second user layer, and thus the demodulation reference signal group with the number of layers being 2 is formed. For the demodulation reference signal groups with the number of layers greater than 2, the demodulation reference signals orthogonal to the determined demodulation reference signals are superimposed layer by layer in a similar manner as described above.

In the examples described below, preferably, the above indication may be broken into multiple parts, one part (e.g., an indication of the layer where the user equipment is located) may be transmitted by higher layer signaling, and another part (e.g., an indication of the demodulation reference signal group, the scrambling code, etc.) may be transmitted by physical layer signaling.

Referring to fig. 4A, a first example of a demodulation reference signal group indication manner according to an embodiment of the present disclosure is shown. In the example shown in fig. 4A, a demodulation reference signal group set consisting of four demodulation reference signal groups DMRS group 0 to DMRS group 3 is shown, which includes two user layers, wherein DMRSs 0 to DMRS3 correspond to the meanings shown in table 1 below:

TABLE 1

DMRS values	Message
		0	OCC ID＝0,n_SCID＝0
1	OCC ID＝0,n_SCID＝1
		2	OCC ID＝1,n_SCID＝0
3	OCC ID＝1,n_SCID＝1

Wherein, OCC _ ID represents ID of orthogonal code applied to each demodulation reference signal, which ensures that demodulation reference signals of different user equipments in the same demodulation reference group are code division orthogonal. Note that, in this example, the OCC _ ID includes only two values of 0 and 1 (for example, when the ID is 0, the OCC code is 11; and when the ID is 1, the OCC code is 10), but as the technology advances, the number of a group of user equipments to be subjected to multi-user superposition transmission may be three or more, that is, the number of layers of the demodulation reference signal group may be three or more, and the OCC _ ID may include more values as long as mutual orthogonality between the respective demodulation reference signals within the demodulation reference signal group to which these OCCs are applied is ensured. n is_SCIDThe value representing the scrambling code, which is typically a pseudo-random sequence, can be used to help distinguish the demodulation reference signals of different user equipments. In the example shown in fig. 4A, the user equipment may be indicated by a demodulation reference signal through consecutive two-bit information, which may be transmitted through physical layer signaling transmitted through the PDCCH, for example, with 4 DMRS groups divided.

According to OCC _ ID and n given in the table above_SCIDThe DMRS involved in the multi-user superposition transmission group may be determined by the user equipment according to a group index included in physical layer signaling (e.g., DCI) transmitted through the PDCCH, and the user layer where the user equipment is located may be determined according to higher layer signaling (e.g., RRC signaling) (e.g., fixedly, a far user equipment is in a first layer, and a near user equipment is in a second layer, and since the distance of the user equipment with respect to the base station should be relatively stable, the layer where the user equipment is located may be notified through the higher layer signaling to reduce signaling overhead), so that the DMRS of the user equipment and the DMRS of other user equipment in the same group may be determined. In the existing LTE system, adjacent antenna ports may occupy the same resource elements to transmit DMRSs and eliminate interference using orthogonal OCC codes, and it can be understood that the OCC _ ID described above may be used instead of an antenna port number to indicate information on the DMRS to the user equipment.

Fig. 4B is a diagram illustrating a second example of a demodulation reference signal group indication manner according to an embodiment of the present disclosure. Unlike the example shown in fig. 4A, in this example, optionally, the set of DMRS groups and the individual DMRS groups may also be in the form of grouping in an OCC orthogonal manner.

In the example shown in fig. 4B, a demodulation reference signal group set consisting of two demodulation reference signal groups, DMRS group 0 and DMRS group 1, is shown, which includes two user layers, wherein the meanings of DMRS0 and DMRS1 corresponding thereto and the values of the corresponding scrambling codes are as shown in tables 2 and 3 below:

TABLE 2

DMRS values	Message
		0	OCC ID＝0
1	OCC ID＝1

TABLE 3

Scrambled code values	Message
		0	n_SCID＝0
1	n_SCID＝1

As shown in fig. 4B, the OCC _ ID of the user equipment of the first user layer within DMRS group 0 is 0, the OCC _ ID of the user equipment of the second user layer is 1, and the OCC _ ID of the user equipment of the first user layer within DMRS group 1 is 1 and the OCC _ ID of the user equipment of the second user layer is 0. Therefore, the user confirms the OCC ID of the user and the OCC ID of the user equipment in the same group according to the index of the DMRS group and the user layer indication notified by the high-layer signaling. Additionally, since user equipments within the same multi-user superposition transmission group can employ the same scrambling code, the base station can reuse 1-bit information to identify (n) the scrambling code_SCID) And sending the DMRS information to the user, wherein the user equipment can specifically determine own DMRS and DMRS of the user equipment in the same group. That is, in the example shown in fig. 4B, the demodulation reference signal indication can be performed for the user equipment through independent two-bit information. These two bits of information may be transmitted, for example, by physical layer signaling transmitted via the PDCCH.

It should be noted that, with the development of the system, the pairing type in the user equipment group performing multi-user superposition transmission may be extended from the pairing of two user equipments each having a single-layer data stream to even more types of pairing between, for example, a far user equipment having a single-layer data stream and a near user equipment having a multi-layer data stream, and thus the demodulation reference signal group set may also become multiple, for example, group set 1 may include only 4 demodulation reference signal groups having a single layer, and group set 2 may include multiple groups such as a demodulation reference signal group having a single layer and a demodulation reference signal group having multiple layers, so that the user equipment may also be notified of the index of the demodulation reference signal group set and the like through the above-mentioned indication.

It can be seen that, according to the above demodulation reference signal group indication manner, signaling overhead for notifying a group of user equipments performing multi-user superposition transmission of demodulation reference signals can be reduced. Further, it should be noted that the above-described manner of indicating the demodulation reference signal is merely an example, and those skilled in the art may also appropriately modify the above-described manner according to the principles of the present disclosure.

Further, it should be noted that for the same set of user equipments, the data stream transmission for the set of user equipments need not utilize space division or diversity gain in a Multiple Input Multiple Output (MIMO) system nor, for example, code division gain of Code Division Multiple Access (CDMA), i.e., the data transmission for the set of user equipments may utilize the same spatial precoding vector or the same transmission diversity or the same orthogonal code, but for a plurality of sets of user equipments performing multi-user superposition transmission, the space division or diversity gain of a MIMO system may also be utilized when one set of user equipments and the other set of user equipments share a MIMO channel together, for example, an example in this case is shown in fig. 5A. Fig. 5A is a diagram illustrating an example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the technique of the present disclosure is applied in a case where there are a plurality of groups of user equipments to be subjected to multi-user superposition transmission and each user equipment has a single-layer data stream.

As shown in fig. 5A, in this example, there are two sets of user equipments to perform multi-user superposition transmission at the same time, i.e., user 0 and user 1 perform multi-user superposition transmission, and user 2, user 3 and user 4 perform multi-user superposition transmission. Note that, in fig. 5A, for convenience of description, the superimposition control unit is divided to include the superimposition encoding module and the reference signal determination module to further clarify the functional division, but it is understood that, in actual implementation, such functional division may not be performed, but the superimposition control unit may be implemented by one unit (e.g., a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), etc.) to implement the corresponding functions.

Specifically, the base station allocates a first power to the data stream of user 0 to obtain a first power signal and allocates a second power to the data stream of user 1 to obtain a second power signal, and the superposition coding module superposes and synthesizes the first power signal and the second power signal into a modulation symbol string. Similarly, the base station allocates a third power to the data stream of the user 2 to obtain a third power signal, allocates a fourth power to the data stream of the user 3 to obtain a fourth power signal, and allocates a fifth power to the data stream of the user 4 to obtain a fifth power signal, and the superposition coding module superposes and synthesizes the third power signal, the fourth power signal and the fifth power signal into a modulation symbol string. Then, the reference signal determination module determines reference signal groups for a group 1 user including user 0 and user 1 and a group 2 user including user 2 to user 4, respectively, from among a plurality of reference signal groups pre-stored in a memory, assuming that the reference signal group S is determined for the group 1 user₀And determining a set of reference signals S for the group 2 users₁. Then, the superposition coding module may superpose the reference signals in each reference signal group according to the transmission power allocated to each user equipment, for example, in a linear superposition manner, and then insert the superposed reference signals into the superposed modulation symbol strings, thereby obtaining a symbol string x 'for the group 1 user and a symbol string x "for the group 2 user, respectively, and then may apply spatial precoding to the symbol string x' for the group 1 user and the symbol string x" for the group 2 user.

Note that the spatial precoding block in fig. 5A is optional. If spatial precoding is applied, then the data streams for user 0 and user 1 (already synthesized to x') use the same spatial precoding vector and the data streams for user 2, user 3 and user 4 (already synthesized to x ") use the same spatial precoding vector, whereas in existing multi-user-multiple input multiple output (MU-MIMO) systems, all users use different spatial precoding vectors. In addition, the advantage of applying spatial precoding here is that time-frequency resources can be further shared by using user groups as units while inter-group interference is eliminated, that is, the space division gain of MIMO is further utilized on the basis of multi-user superposition transmission to enable the first group of users (users 0 and 1) and the second group of users (

users

2, 3 and 4) to share the time-frequency resources for transmission, so that according to the MUST + MU-MIMO two-level resource sharing mechanism, the utilization rate of resources can be greatly improved.

Further, it should be noted that, in the example shown in fig. 5A, for convenience of description, the superimposed demodulation reference signals are shown to be inserted into the superimposed data streams, however, in actual transmission, the demodulation reference signals of the respective user equipments are respectively inserted into the corresponding data streams to be superimposed by the superposition coding module.

When the user equipment performs data transmission with the base station, the user equipment may include a single-layer data stream (one-way data stream) or a multi-layer data stream (multiple-way data stream), for example, for a user equipment closer to the base station, the user equipment may have the multi-layer data stream under a good channel condition, and for a user equipment farther from the base station, the user equipment usually has only the single-layer data stream. When the user equipment with the multilayer data stream and the user equipment with the single-layer data stream perform multi-user superposition transmission, one layer of the multilayer data stream and the single-layer data stream of other user equipment can be selected to perform multi-user superposition transmission, or the multilayer data stream can be subjected to spatial precoding to form a transmission stream and then superposed with the data streams of other user equipment. Preferably, all the user equipments have only a single layer data stream, which can reduce the complexity of the system and is easy to implement. The following will describe three cases, with reference to fig. 5A to 5C, respectively, that is, a case where all the user equipments have only a single-layer data stream, a case where the multi-layer data streams are overlapped after being spatially precoded into one transmission stream, and a case where only one layer of the multi-layer data streams is selected to perform multi-user overlap transmission with the data streams of other user equipments, and the data streams of the remaining layers are transmitted in a conventional manner.

As shown in fig. 5A, in this example, each ue has only a single-layer data stream, and the multi-user superposition transmission may be performed separately for each ue in each ue group in the manner described above. The specific stacking manner can be referred to the description of the corresponding position, and is not described herein again.

Fig. 5B is a diagram illustrating a first example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the technique of the present disclosure is applied in a case where a user equipment has a multi-layer data stream.

As shown in fig. 5B, in this example, user 0 and user 1 both include two layers of data streams, and demodulation reference signal s may be allocated to user 0's two layers of data streams respectively₀And s₁And allocates demodulation reference signal s to the two-layer data stream of user 1₂And s₃. Unlike the example shown in fig. 5A, before superposition coding is performed on the demodulation reference signals of user 0 and user 1, two layers of data streams of user 0 and user 1 are first spatially precoded to become one transmission stream (at this time, the precoded demodulation reference signal of user 0 is s)₀+s₁The precoded demodulation reference signal of user 1 is s₂+s₃) Then, the superposition coding module superposes the precoded single-channel transmission streams of the user 0 and the user 1 in a similar manner to the single-layer data stream shown in fig. 5A, so as to obtain a superposed demodulation reference signal s.

Fig. 5C is a diagram illustrating a second example of demodulation reference signal transmission in a wireless communication system of multi-user superposition transmission to which the technique of the present disclosure is applied in a case where a user equipment has a multi-layer data stream.

As shown in fig. 5C, in this example, user 0 and user 1 both include two layers of data streams, and select data layer 1 of user 0 and data layer 1 of user 1 to perform multi-user superposition transmission, where a specific superposition transmission manner is the same as that described above, and is not described here again. Whereas for data layer 0 for user 0 and data layer 0 for user 1, the transmission may be performed in a conventional manner.

Here, it should be noted that the superposition coding module, the reference signal determination module, and the spatial precoding module in fig. 5B and 5C have the same functions and configurations as the corresponding modules described above with reference to fig. 5A, and a description thereof will not be repeated.

Preferably, each user equipment has only a single-layer data stream, so that the superposition control unit 202 inserts demodulation reference signals supporting only a single-layer data stream into the data streams of each user equipment, respectively, which can reduce system complexity.

Furthermore, preferably, as shown in fig. 5A to 5C, the apparatus 200 may further include a storage unit that may be configured to store information of a demodulation reference signal group set including a plurality of reference signal groups, wherein the plurality of demodulation reference signals included in each demodulation reference signal group are code-division orthogonal to each other, and the superposition control unit may read the storage unit to determine the reference signal groups for the respective user equipment groups.

Preferably, the apparatus 200 may be an independent processing chip located on the base station side, and transmit the superimposed demodulation reference signal obtained by the superimposition control unit 202 and the instruction generated by the instruction generation unit 204 to at least the first user equipment through the external communication unit, or alternatively, the apparatus 200 may also be the base station itself, and in this case, the apparatus 200 may further include a transmission unit that may be configured to transmit the superimposed demodulation reference signal obtained by the superimposition control unit 202 and the instruction generated by the instruction generation unit 204 to at least the first user equipment.

Next, a functional configuration example of a device on the user equipment side corresponding to the device on the base station side in the above-described embodiment will be described with reference to fig. 6. Fig. 6 is a block diagram showing a functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure.

As shown in fig. 6, the apparatus 600 according to this embodiment may include an equivalent channel estimation unit 602 and a data demodulation unit 604.

The equivalent channel estimation unit 602 may be configured to estimate an equivalent channel corresponding to a data stream of the target user equipment and equivalent channels corresponding to data streams of other user equipments according to the indication from the base station regarding the superimposed demodulation reference signals of the target user equipment and other user equipments and the demodulation reference signals of other user equipments, where the demodulation reference signals of the target user equipment and the demodulation reference signals of other user equipments are respectively inserted into the data streams of the respective user equipments, and the data streams of the respective user equipments are transmitted by the base station at a specific transmission power and with the same time-frequency resources without utilizing mimo performance gain and/or code division multiplexing. The specific channel estimation process is the same as that in the prior art, and is not described herein again.

Preferably, as described above, the indication may be included in physical layer signaling (e.g., DCI), higher layer signaling (e.g., RRC signaling), or MAC signaling, or may also be included in part in physical layer signaling and another part in higher layer signaling, so that the equivalent channel estimation unit 602 may obtain the corresponding demodulation reference signal indication according to the signaling.

Preferably, the demodulation reference signals for the respective user equipments have different orthogonal codes, so that the demodulation reference signals for the respective user equipments are transmitted to the respective user equipments on the same resource element. Furthermore, it is preferable that each user equipment has only a single-layer data stream, and demodulation reference signals supporting only the single-layer data stream are inserted into the data stream of each user equipment. Further, it is preferable that demodulation reference signals with respect to respective user equipments are allocated with a specific transmission power, and the superimposed demodulation reference signals are superimposed according to the allocated transmission power, and a manner of superimposing the demodulation reference signals with respect to the respective user equipments and a manner of superimposing data streams of the respective user equipments may be the same or different. Further, the transmission power allocated to the demodulation reference signal with respect to each user equipment is the same as the transmission power allocated to the data stream of the user equipment.

The equivalent channel estimation unit 602 may be further configured to determine an index of a reference signal group for a group of user equipments including the target user equipment and the other user equipments according to an indication from the base station, wherein a number of demodulation reference signals in the reference signal group is greater than or equal to a number of user equipments in the group of user equipments. Specifically, in the case of the static mode described above, the target user equipment may obtain the corresponding demodulation reference signal from its memory according to the index of the reference signal group notified by the base station, and in the case of the semi-static mode, the target user equipment may know the information of the demodulation reference signal group according to the broadcast signaling or RRC signaling from the base station.

The equivalent channel estimation unit 602 may be further configured to determine demodulation reference signals for other user equipments according to the determined indexes and information on the demodulation reference signals of the target user equipment (e.g., sequence numbers of the demodulation reference signals of the target user equipment in the reference signal group or OCC information) contained in the indication, and the data demodulation unit 604 may demodulate the data of the multi-user superposition transmission according to the determined demodulation reference signals for the target user equipment itself and the other user equipments.

The equivalent channel estimation unit 602 may be further configured to determine, according to the indication, an indication manner of the demodulation reference signal of the user equipment, where the indication manner includes a demodulation reference signal group indication manner and a legacy demodulation reference signal indication manner, and the indication manner of the demodulation reference signal of at least one user equipment (e.g., a legacy user equipment farthest from the base station) in the group of user equipments performing the multi-user superposition transmission is the legacy demodulation reference signal indication manner. Preferably, for the user equipment to use the demodulation reference signal group indication mode, the demodulation reference signals supporting only a single-layer data stream can be selected.

The data demodulation unit 604 may be configured to demodulate the data of the multi-user superposition transmission according to the estimated equivalent channels (including the equivalent channel of the target user equipment itself and the equivalent channels of other user equipments). The specific process of demodulating the data stream according to the equivalent channel is the same as that in the prior art, and is not described herein again.

Instead of the prior art in which the base station notifies each user equipment of its power allocation coefficient, according to the technique of the present disclosure, the power allocation coefficients of its own and other user equipments may be calculated by the user equipment from the estimated equivalent channel, and the data stream may be demodulated based on the calculated power allocation coefficients. This case will be described in detail below with reference to fig. 7. Fig. 7 is a block diagram showing another functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to the first embodiment of the present disclosure.

As shown in fig. 7, the apparatus 700 according to this example may include an equivalent channel estimation unit 702, a power allocation coefficient determination unit 704, and a data demodulation unit 706. Here, the functional configurations of the equivalent channel estimation unit 702 and the data demodulation unit 706 are substantially the same as those of the equivalent channel estimation unit 602 and the data demodulation unit 604 described above with reference to fig. 6, and a description thereof will not be repeated. Only a functional configuration example of the power distribution coefficient determining unit 704 will be described in detail below.

The power distribution coefficient determining unit 704 may be configured to determine power distribution coefficients of the target user equipment and other user equipments according to the equivalent channel estimated by the equivalent channel estimating unit 702.

Specifically, assume that the base station selects user 0 and user 1 for multi-user superposition transmission, and the demodulation reference signals for user 0 and user 1 are s respectively₀And s₁Demodulation reference signal and demodulation reference signal s after superposition received in equivalent channel estimation unit 702₀And s₁To estimate the equivalent channel h corresponding to the data stream of user 0₀Equivalent channel h corresponding to user 1's data stream₁Thereafter, the power distribution coefficient determining unit 704 may determine the equivalent channel h according to the equivalent channel h₀And h₁Deriving demodulation reference signal s₀And s₁Experienced common channel h (i.e., physical channel) and power distribution coefficient α for user 0 and user 1₀And alpha₁In particularGround can be obtained, for example, by solving the following equation set (1):

where P is the total transmit power of the base station and may also be informed to the user equipment by the base station, e.g., through the above indication. Alternatively, the base station may not notify the user equipment of the total transmission power, so that the user equipment may solve the power allocation coefficient of each user equipment according to the following equation:

the data demodulation unit 706 may then be further configured to demodulate the data of the multi-user superposition transmission according to the determined power distribution coefficients.

Specifically, as an example, the data demodulation unit 706 can be configured to recover the constellation diagram according to the determined power allocation coefficient so as to demodulate the data of the multi-user superposition transmission. It should be noted that this data demodulation approach is generally applicable to the case where the data streams are superimposed in a non-linear fashion.

Alternatively, as another example, after the power allocation coefficient is determined, the demodulation order of the data streams may be determined, that is, generally, the data demodulation unit 706 may first demodulate the data stream of the user equipment with a large power allocation coefficient, and if the demodulated data stream is not the data stream of the target user equipment, may cancel the interference in a non-linear interference cancellation manner by using the data streams of other user equipments as the interference, and then demodulate the data stream of the target user equipment based on the equivalent channel of the target user equipment. It should be noted that this data demodulation approach is generally applicable to the case where the data streams are superimposed in a linear fashion.

It should be noted that the power allocation coefficient determining unit is optional, and the determined power allocation coefficient can be used for subsequent retransmission and the like. That is, in the case where only the data demodulation operation needs to be performed, the data demodulation can also be achieved without determining the power distribution coefficients of the respective user equipments.

Instead of determining the power allocation coefficients of the respective user equipments in the above example, the demodulation order of the data streams of the respective user equipments may also be determined without determining the power allocation coefficients. Next, this case will be described in detail with reference to fig. 8. Fig. 8 is a block diagram showing still another functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to the first embodiment of the present disclosure.

As shown in fig. 8, the apparatus 800 according to this example may include an equivalent channel estimation unit 802, a demodulation order determination unit 804, and a data demodulation unit 806. Here, the functional configurations of the equivalent channel estimation unit 802 and the data demodulation unit 806 are substantially the same as those of the equivalent channel estimation unit 602 and the data demodulation unit 604 described above with reference to fig. 6, and the details thereof will not be described here. Only a functional configuration example of the demodulation order determination unit 804 will be described in detail below.

The demodulation order determination unit 804 may be configured to determine a data demodulation order of the target user equipment and the other user equipments according to the equivalent channel estimated by the equivalent channel estimation unit 802. Specifically, as an example, the larger the equivalent channel, the earlier the data demodulation order thereof. It should be noted that although the data demodulation order is determined directly from the estimated equivalent channel in this example, the power allocation coefficients of the respective user equipments may be calculated first and then the data demodulation order may be determined as in the example described above with reference to fig. 7, that is, the functional blocks in fig. 7 and 8 may be combined.

The data demodulation unit 806 may then be further configured to demodulate the data of the multi-user superposition transmission according to the determined data demodulation order. Specifically, if it is determined that the data stream of the target user equipment is demodulated first, the data demodulation unit 806 may demodulate the data stream of the target user equipment directly according to the equivalent channel. However, if the data stream demodulated first is not the data stream of the target user equipment, the data demodulation unit 806 may be further configured to demodulate the data stream of the target user equipment in a non-linear interference cancellation manner according to the determined data demodulation order, that is, demodulate the data stream of the other user equipment based on the equivalent channel of the target user equipment after the data stream of the other user equipment is cancelled as interference.

It should be understood that the above-mentioned apparatuses 600 to 800 may be independent processing chips on the user equipment side and receive the superimposed demodulation reference signal and the related indication from the base station through an external receiving unit, or alternatively, the apparatuses 600 to 800 may also be the user equipment itself, and in this case, the apparatuses 600 to 800 may further include a receiving unit configured to receive the superimposed demodulation reference signal and the above-mentioned demodulation reference signal indication from the base station.

Further, it should be noted that the apparatuses 600 to 800 on the user equipment side described herein correspond to the apparatus 200 on the base station side described above, and therefore, contents not described in detail herein may refer to the description of the corresponding positions above, and will not be repeated here.

To facilitate understanding of the demodulation reference signal transmission manner according to the first embodiment of the present disclosure, a signaling interaction procedure between the base station side and the user equipment side in this embodiment will be systematically described below with reference to a flowchart shown in fig. 9. Fig. 9 is a flowchart illustrating a signaling interaction procedure in a wireless communication system for multi-user superposition transmission according to a first embodiment of the present disclosure.

As shown in fig. 9, in step S901, the base station may select a corresponding demodulation reference signal group for a group of user equipments to perform multi-user superposition transmission, and in step S902, notify the user equipments of an index of the demodulation reference signal group. It should be noted that for a fixed set of user equipments, the set of demodulation reference signals selected for it is typically fixed, and therefore, the user equipments typically only need to be informed once. For example, assume that there are four demodulation reference signals s in total₀、s₁、s₂And s₃. Wherein s is₀And s₁Sharing time frequency resource, orthogonal in code division mode and forming demodulation reference signal set S₀＝{s₀，s₁}；s₂And s₃Sharing time frequency resource, orthogonal in code division mode and forming demodulation reference signal set S₁＝{s₂，s₃}. Wherein S is₀And S₁The demodulation reference signal (i.e., s) contained in₀And s₁And s₂And s₃) Are orthogonal in a time division or frequency division manner. Here, suppose that the base station selects user 0 to transmit with user 1 in a multi-user superposition manner, and transmits coded bit streams c respectively₀And c₁And assuming that user 0 is the target user equipment, a demodulation reference signal group S is selected for user 0 and user 1₀And informs the user equipment of the index of the demodulation reference signal group. Preferably, the base station may further notify the sequence numbers of the demodulation reference signals corresponding to the

users

0 and 1 in the group to the

users

0 and 1.

Next, in step S903, the base station sets power distribution coefficients α for user 0 and user 1, respectively₀And alpha₁In which α is₁＝1-α₀A 1 is to₀And s₁Linear superposition after power coefficient weighting is carried out to obtain

The stream identifier of the modulation symbol after multi-user superposition transmission is x, and x can be a linear superposition result or a nonlinear superposition result. Then, in step S904, the base station transmits the superimposed demodulation reference signal to the user equipment. Specifically, the base station inserts s ' into the superimposed modulation symbol stream x to obtain a symbol string x ', and precodes and maps the symbol string x ' to time-frequency resource units in the OFDM symbols for transmission.

Then, in step S905, the ue knows the demodulation reference signals corresponding to the data streams of user 0 and user 1 according to the indexes of the reference signal groups. Specifically, the ue obtains the demodulation reference signal group used by the base station based on the index of the demodulation reference signal group, and then obtains the demodulation reference signal corresponding to its data stream and the demodulation reference signals corresponding to other data streams according to the user serial number. Or alternatively, in the case where the configuration of the reference signal group is defined in advance on the base station side and the user equipment side, the user equipment can determine the demodulation reference signals for the respective user equipments only from the indexes of the reference signal group.

Next, in step S906, the ue estimates an equivalent channel corresponding to each data stream according to the demodulation reference signal corresponding to the data stream of each user. Specifically, the user 0 obtains the equivalent channel h corresponding to the own data stream based on the demodulation reference signal corresponding to the own data stream₀Based on the demodulation reference signal corresponding to user 1, the equivalent channel h corresponding to the data stream is obtained₁。

Next, in step S907, the user equipment derives parameters such as power allocation coefficients, data demodulation orders, and the like of the physical channels and the respective user equipments from the estimated equivalent channels. Specifically, user 0 is based on the estimated equivalent channel h₀And h₁To deduce s₀And s₁Experienced common channel h and power distribution coefficient alpha₀And alpha₁This can be obtained by solving the following system of equations:

α₀+α₁＝1

finally, in step S908, the user equipment may preferentially demodulate the data stream with the larger power allocation coefficient according to the above determined power allocation coefficient. If the data stream is not that of target user equipment 0, then the equivalent channel h according to user 1 is used₁Demodulate the data stream c of user 1₁Then c is added to the received signal₁As interference cancellation, then based on the equivalent channel h₀Demodulate its own data stream c₀. Alternatively, the user equipment may also recover the constellation diagram according to the power allocation coefficient, so as to demodulate the data stream corresponding to the user equipment.

It should be noted that the signaling interaction process shown in fig. 9 is merely an example and not a limitation, and those skilled in the art may also make modifications to the above process in accordance with the principles of the present disclosure. For example, in step S907, the ue may not determine parameters such as power allocation coefficient and demodulation reference sequence, and may perform data demodulation directly according to the equivalent channel estimation. For another example, when the base station determines the demodulation reference signal group in the semi-static manner, the user equipment does not have to be notified of the index of the demodulation reference signal group in step S902, but needs to be notified of the configuration of the specific reference signal group at that time. Further, for example, the base station may also notify the user equipment of the total transmission power of the base station, so that the user equipment may calculate the power allocation coefficient of each user equipment by using the above equation set (1) according to the total transmission power and the estimated equivalent channel.

The above describes an example of performing multi-user superposition transmission on a plurality of demodulation reference signals by respectively inserting a respective demodulation reference signal into a data stream of each of a plurality of user equipments performing multi-user superposition transmission according to the first embodiment of the present disclosure with reference to fig. 2 to 9, and it can be seen that, according to this embodiment, since the base station side does not need to notify the user equipments of a dynamically changing power allocation coefficient, signaling overhead can be greatly reduced. Next, a demodulation reference signal transmission scheme according to a second embodiment of the present disclosure, that is, a common demodulation reference signal is inserted in superimposed data streams of a plurality of user equipments, will be described.

Second embodiment

Fig. 10 is a block diagram showing a functional configuration example of an apparatus on the base station side in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure.

As shown in fig. 10, the apparatus 1000 according to this example may include an insertion control unit 1002 and an instruction generation unit 1004.

The insertion control unit 1002 may be configured to insert a common demodulation reference signal in the superimposed data streams of the plurality of user equipments. As described above with reference to fig. 1, in this embodiment, a common demodulation reference signal is inserted into the superimposed data streams of a plurality of user equipments instead of inserting respective demodulation reference signals into the data streams of the respective user equipments, unlike the demodulation reference signal transmission scheme described in the first embodiment.

The indication generating unit 1004 may be configured to generate, for at least a first user equipment of the plurality of user equipments, an indication of power allocation coefficients corresponding to data streams of respective ones of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission. Preferably, as described above, the indication may be included in physical layer signaling (e.g., DCI), higher layer signaling (e.g., RRC signaling), or MAC layer signaling, and may also be included in part in physical layer signaling and in part in higher layer signaling.

In this embodiment, different from the first embodiment, since only the common demodulation reference signal is transmitted to all the user equipments, in order to enable the user equipments to demodulate the respective target data streams, it is also necessary to notify the respective user equipments of the corresponding power allocation coefficients. Therefore, the signaling overhead of this demodulation reference signal transmission scheme is larger than that of the first embodiment.

Preferably, the insertion control unit 1002 is further configured to allocate full transmit power for the common demodulation reference signal. It can be appreciated that although the notification of the power allocation coefficient increases signaling overhead, since the common demodulation reference signal is transmitted with full transmission power in this embodiment, the accuracy of channel estimation of the user equipment can be greatly improved compared to the prior art in which the demodulation reference signals of the respective user equipments are transmitted with only partial transmission power separately.

Similar to the apparatus 200 of the base station side described above, the apparatus 1000 may be a separate processing chip located at the base station side and transmit the common demodulation reference signal determined by the apparatus 1000 and the indication on the power distribution coefficient of each user equipment to the user equipment through an external communication unit, or alternatively, the apparatus 1000 may also be a base station itself, and in this case, the apparatus 1000 may further include a transmitting unit that may be configured to transmit the common demodulation reference signal and the indication described above to at least the first user equipment.

Corresponding to the apparatus 1000, a functional configuration example of an apparatus on the user equipment side in the second embodiment will be described below.

Fig. 11 is a block diagram showing a functional configuration example of an apparatus on the user equipment side in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure.

As shown in fig. 11, an apparatus 1100 according to this example may include an equivalent channel estimation unit 1102 and a data demodulation unit 1104.

The equivalent channel estimation unit 1102 may be configured to estimate an equivalent channel corresponding to the superimposed data stream from the base station according to a common demodulation reference signal from the base station, wherein the common demodulation reference signal is inserted in the superimposed data stream. As described above, since the common demodulation reference signal is transmitted at full transmission power, the ue can estimate an equivalent channel corresponding to the full power signal, i.e., an equivalent channel corresponding to the superimposed data stream, according to the received common demodulation reference signal.

The data demodulation unit 1104 can be configured to demodulate data of the multi-user superposition transmission according to the estimated equivalent channel and an indication from the base station about power distribution coefficients of the target user equipment and other user equipments. Specifically, the data demodulation unit 1104 may be further configured to determine an equivalent channel corresponding to the data stream of the target user equipment and equivalent channels corresponding to the data streams of other user equipments according to the estimated equivalent channels and the indication on the power distribution coefficient, and demodulate data of the multi-user superposition transmission according to the determined equivalent channels of the respective user equipments. The specific process of demodulating data according to the equivalent channel is the same as that in the prior art, and is not described herein again.

As an example, the data demodulation unit 1104 can be further configured to demodulate data of the multi-user superposition transmission in a non-linear interference cancellation manner by preferentially demodulating a data stream corresponding to a user equipment having a large power allocation coefficient according to the indication on the power allocation coefficient. This generally applies to the case where the data streams of the individual user equipments are superimposed in a linear manner.

Alternatively, as another example, the data demodulation unit 1104 may be further configured to demodulate data of the multi-user superposition transmission by determining power allocation coefficients of respective user equipments according to the indication on the power allocation coefficients to restore the constellation. Specifically, the base station side and the user equipment side may decide in advance which bits of the received symbol bit string the data stream of each user equipment corresponds to, so that the user equipment may determine the data stream of the target user equipment by recovering the constellation diagram. It will be appreciated that this approach is generally applicable where the data streams of the respective user devices are superimposed in a non-linear manner.

It should be understood that, similar to the apparatuses 600 to 800 on the user equipment side described above, the apparatus 1100 on the user equipment side according to this embodiment may be a separate processing chip on the user equipment side and receive the common demodulation reference signal and the indication on the power allocation coefficient from the base station through an external communication unit, or alternatively, the apparatus 1100 may also be the user equipment itself, and in this case, the apparatus 1100 may further include a receiving unit that may be configured to receive the common demodulation reference signal and the indication on the power allocation coefficient from the base station.

To facilitate understanding of the demodulation reference signal transmission manner according to the second embodiment of the present disclosure, a signaling interaction procedure between the base station side and the user equipment side in this embodiment will be systematically described below with reference to a flowchart shown in fig. 12. Fig. 12 is a flowchart illustrating a signaling interaction procedure in a wireless communication system for multi-user superposition transmission according to a second embodiment of the present disclosure.

As shown in fig. 12, in step S1201, the base station may select one common demodulation reference signal for a group of user equipments to perform multi-user superposition transmission, and inform the user equipments of an index of the common demodulation reference signal in step S1202. It should be noted that for a fixed set of user equipments, the common demodulation reference signal selected for it is typically fixed, and therefore typically only needs to be signalled to the user equipment once. For example, assume that there are four demodulation reference signals s in total₀、s₁、s₂And s₃The base station selects user 0 and user 1 to perform multi-user superposition transmissionTransmitting the coded bit stream c₀And c₁And here it is assumed that user 0 is the target user equipment, a common demodulation reference signal set s is selected for user 0 and user 1₀And notifies, for example, an index of the demodulation reference signal to the user equipment.

Next, in step S1203, the base station sets power allocation coefficients α for user 0 and user 1, respectively₀And alpha₁And informs the user equipment of where₁＝1-α₀. The stream identifier of the modulation symbol after multi-user superposition transmission is x, and x can be a linear superposition result or a nonlinear superposition result. Then, in step S1204, the base station demodulates the reference signal S for the common signal S₀Full power division coefficient 1 is allocated, and common demodulation reference signal S is assigned in step S1205₀Sending to the user equipment, specifically, the base station inserts s into the superimposed modulation symbol stream x₀A symbol string x' is obtained and precoded and mapped to time-frequency resource elements in the OFDM symbol for transmission.

Then, in step S1206, user 0 and user 1 are based on the common demodulation reference signal S₀Obtaining an equivalent channel h corresponding to the symbol stream x, and then distributing the channel h according to the power distribution coefficient α in step S1207₀And alpha₁Obtaining the equivalent channel h corresponding to the own data stream₀＝α₀h，h1＝α₁h。

Finally, in step S1208, the user equipment may preferentially demodulate the data stream with the larger power allocation coefficient according to the notification of the power allocation coefficient. If the data stream is not the data stream of target user 0, then the equivalent channel h according to user 1₁Demodulate the data stream c of user 1₁Then c is added to the received signal₁As interference cancellation, then based on the equivalent channel h₀Demodulate its own data stream c₀. Alternatively, the user equipment may also recover the constellation diagram according to the power allocation coefficient, so as to demodulate the data stream corresponding to the user equipment.

It should be noted that the signaling interaction process shown in fig. 12 is merely an example and not a limitation, and those skilled in the art may also make modifications to the above process in accordance with the principles of the present disclosure. For example, in a case where the composition of a group of user equipments to be subjected to multi-user superposition transmission is fixed and the base station side and the user equipment side agree in advance on a common demodulation reference signal to be used for the group of user equipments, the base station side may not select the common demodulation reference signal for the target user equipment group and notify the user equipment of the index of the common demodulation reference signal, that is, the processing in steps S1201 and S1202 may be omitted.

Functional configuration examples of a base station side device and a user equipment side device in a wireless communication system are described above with reference to fig. 1 to 12, respectively, but it should be understood that the above description is only an example and not a limitation, and a person skilled in the art may add, delete, combine, sub-combine, or change the above-described respective functional modules according to the principles of the present disclosure, and such modifications should be considered to fall within the scope of the present disclosure.

Corresponding to the above device embodiments, the present disclosure also provides the following method embodiments.

Fig. 13 is a flowchart illustrating a process example of a method on the base station side in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure.

As shown in fig. 13, the method starts in step S1302, a device on a base station side inserts a demodulation reference signal corresponding to a data stream into a data stream of each user equipment in a group of user equipments including a plurality of user equipments respectively and superposes the demodulation reference signals corresponding to the data streams of the respective user equipments, wherein a specific transmission power is allocated to the data stream of the respective user equipment so that the data stream of the respective user equipment is transmitted to the plurality of user equipments with the same time-frequency resources without using mimo performance gain and/or code division multiplexing.

Preferably, in step S1302, a specific transmission power may be allocated to the demodulation reference signal corresponding to the data stream of each user equipment, and the demodulation reference signals corresponding to the data streams of each user equipment may be superimposed according to the allocated power. Preferably, the demodulation reference signals corresponding to the data streams of the respective user equipments have different orthogonal codes, such that the demodulation reference signals corresponding to the data streams of the respective user equipments are transmitted to the respective user equipments on the same resource element, the respective user equipments have only single-layer data streams, and the demodulation reference signals supporting only single-layer data streams are respectively inserted into the data streams of the respective user equipments. Preferably, the demodulation reference signals corresponding to the data streams of the respective user equipments are superimposed in a different manner from the data streams of the respective user equipments, and the transmission power allocated to the demodulation reference signals corresponding to the data streams of the respective user equipments is the same as the transmission power allocated to the data streams.

Then, the method proceeds to step S1304, and in step S1304, an indication of demodulation reference signals corresponding to data streams of other user equipments in the plurality of user equipments is generated for at least a first user equipment in the plurality of user equipments, so as to assist the first user equipment in demodulating data of the multi-user superposition transmission. Preferably, the indication may be included in physical layer signaling (e.g., DCI), higher layer signaling (e.g., RRC signaling), or MAC layer signaling, or may be divided into different portions for inclusion in the physical layer signaling and the higher layer signaling, respectively.

Preferably, in step S1302, a reference signal group for a group of user equipments may be further determined from a plurality of reference signal groups respectively composed of a plurality of demodulation reference signals, wherein the number of demodulation reference signals included in the determined reference signal group is the same as the number of user equipments included in the group of user equipments, and preferably, the indication further includes an index for the determined reference signal group. Further preferably, the indication further comprises information including a demodulation reference signal for the first user equipment in the determined reference signal group. Preferably, the indication further includes at least one bit for indicating to the user equipment an indication manner regarding the demodulation reference signal, and the indication manner includes a demodulation reference signal group indication manner and a legacy demodulation reference signal indication manner. Furthermore, it is preferable to use a conventional demodulation reference signal indication scheme for at least a second user equipment (e.g., the user equipment farthest from the base station) in the group of user equipments.

In addition, the storage unit may be further read to determine a reference signal group for a group of user equipments, the storage unit storing information of a demodulation reference signal group set including a plurality of reference signal groups, wherein the plurality of demodulation reference signals included in each demodulation reference signal group are code-division orthogonal to each other.

Furthermore, preferably, in case the method is performed in a base station, the method may further comprise a step for transmitting the superimposed demodulation reference signal and indication to at least the first user equipment.

It should be noted that the embodiments of the method described herein correspond to the embodiments of the apparatus 200 described above, and details that are not described herein may be referred to the description of the corresponding locations above, and are not repeated here.

Fig. 14 is a flowchart illustrating a process example of a method at a base station side in a wireless communication system for multi-user superposition transmission according to another embodiment of the present disclosure.

As shown in fig. 14, the method starts with step S1402, and in step S1402, a common demodulation reference signal is inserted in the superimposed data streams of the plurality of user equipments by the apparatus on the base station side. Preferably, in step S1402, full transmission power is also allocated for the common demodulation reference signal.

The method then proceeds to step S1404, where in step S1404, an indication is generated for at least a first user equipment of the plurality of user equipments regarding power distribution coefficients corresponding to data streams of respective ones of the plurality of user equipments to assist the first user equipment in demodulating data of the multi-user superposition transmission.

Furthermore, preferably, in case the method is performed in a base station, the method may further comprise a step for transmitting the common demodulation reference signal and the indication to at least the first user equipment.

It should be noted that the embodiments of the method described herein correspond to the embodiments of the apparatus 1000 described above, and details that are not described herein may be referred to the description of the corresponding locations above, and are not repeated here.

Fig. 15 is a flowchart illustrating a process example of a method on a user equipment side in a wireless communication system for multi-user superposition transmission according to an embodiment of the present disclosure.

As shown in fig. 15, the method starts in step S1502, and in step S1502, an equivalent channel corresponding to a data stream of a target user equipment and an equivalent channel corresponding to a data stream of other user equipment are estimated by a device on the side of the user equipment according to an indication from a base station about a demodulation reference signal of the target user equipment and the demodulation reference signal of the other user equipment after superposition and the equivalent channel corresponding to the data stream of the other user equipment, wherein the demodulation reference signal of the target user equipment and the demodulation reference signal of the other user equipment are respectively inserted into the data streams of the respective user equipments, and the data streams of the respective user equipments are transmitted by the base station at a specific transmission power and with the same time-frequency resource without utilizing mimo performance gain and/or code division multiplexing. Preferably, the indication is obtained from physical layer signalling and/or MAC layer signalling and/or higher layer signalling from the base station. Further, it is preferable that demodulation reference signals with respect to respective user equipments are allocated with a specific transmission power, and the demodulation reference signals after being superimposed are superimposed according to the allocated transmission power. Further, the manner of superimposing the demodulation reference signals with respect to the respective user equipments is different from the manner of superimposing the data streams with respect to the respective user equipments, and the transmission power allocated to the demodulation reference signals with respect to the respective user equipments is the same as the transmission power allocated to the data streams with respect to the user equipments. Preferably, the demodulation reference signals for the respective user equipments have different orthogonal codes, so that the demodulation reference signals for the respective user equipments are transmitted to the respective user equipments on the same resource element. Further, it is preferable that each user equipment has only a single-layer data stream, and demodulation reference signals supporting only the single-layer data stream are inserted into the data stream of each user equipment.

Next, the method proceeds to step S1504, and in step S1504, data of the multi-user superposition transmission may be demodulated according to the estimated equivalent channel.

Preferably, the method may further include the step of determining power allocation coefficients of the target user equipment and other user equipments according to the estimated equivalent channel, and the data of the multi-user superposition transmission may be demodulated according to the determined power allocation coefficients in step S1504. Preferably, in step S1504, the constellation diagram can also be recovered according to the determined power distribution coefficient, so as to demodulate the data of the multi-user superposition transmission.

Further, preferably, the method may further include a step of determining a data demodulation order of the target user equipment and the other user equipments according to the estimated equivalent channel, and the data of the multi-user superposition transmission may be demodulated according to the determined data demodulation order in step S1504. Preferably, in step S1504, the data of the multi-user superposition transmission may also be demodulated in a non-linear interference cancellation manner according to the determined data demodulation order.

Preferably, in step S1502, an index of a reference signal group for a group of user equipments including the target user equipment and other user equipments may be determined according to the indication, wherein the number of demodulation reference signals in the reference signal group is greater than or equal to the number of user equipments in the group of user equipments. Further, preferably, in step S1502, demodulation reference signals for other user equipments may be determined according to the index and information on the demodulation reference signal of the target user equipment contained in the indication, and in step S1504, data of the multi-user superposition transmission may be demodulated according to the determined demodulation reference signals.

Preferably, in step S1502, an indication manner of the demodulation reference signal of the target ue may be determined according to the indication, the indication manner includes a demodulation reference signal group indication manner and a legacy demodulation reference signal indication manner, and the indication manner of the demodulation reference signal of at least one ue in the group of ues is the legacy demodulation reference signal indication manner. Preferably, for the user equipment to use the demodulation reference signal group indication mode, the demodulation reference signals supporting only a single-layer data stream can be selected.

Furthermore, preferably, in the case where the method is performed in a user equipment, the method may further include a step for receiving the superimposed demodulation reference signal and the above indication from the base station.

It should be noted that the embodiments of the method described herein correspond to the embodiments of the apparatuses 600 to 800 described above, and details that are not described herein in detail can be referred to the description of the corresponding positions above, and are not repeated here.

Fig. 16 is a flowchart illustrating a process example of a method at a user equipment side in a wireless communication system for multi-user superposition transmission according to another embodiment of the present disclosure.

As shown in fig. 16, the method starts in step S1602, and in step S1602, an equivalent channel corresponding to a superimposed data stream from a base station is estimated according to a common demodulation reference signal from the base station, wherein the common demodulation reference signal is inserted into the superimposed data stream.

The method then proceeds to step S1604 where the data of the multi-user superposition transmission is demodulated according to the estimated equivalent channel and the indication from the base station about the power allocation coefficients of the target user equipment and other user equipments in step S1604.

Preferably, in step S1604, the equivalent channel corresponding to the data stream of the target user equipment and the equivalent channel corresponding to the data stream of the other user equipment are determined according to the estimated equivalent channels and the indication, and the data of the multi-user superposition transmission is demodulated according to the determined equivalent channels of the respective user equipments. Preferably, in step S1604, the data of the multi-user superposition transmission is demodulated in a non-linear interference cancellation manner according to the data stream corresponding to the user equipment indicating the high priority demodulation power allocation coefficient. Further, it is preferable that in step S1604, the data of the multi-user superposition transmission is demodulated by determining the power allocation coefficient of each user equipment according to the instruction so as to restore the constellation.

Further, preferably, in case the method is performed in a user equipment, the method may further comprise a step for receiving a common demodulation reference signal from the base station and the above indication.

It should be noted that the embodiments of the method described herein correspond to the embodiments of the apparatus 1100 described above, and details that are not described herein may be referred to the description of the corresponding locations above, and are not repeated herein.

It should be noted that although the above describes a process example of a method in a wireless communication system according to an embodiment of the present disclosure, this is only an example and not a limitation, and a person skilled in the art may modify the above embodiment according to the principle of the present disclosure, for example, steps in various embodiments may be added, deleted, combined, or the like, and such modifications fall within the scope of the present disclosure.

Furthermore, according to an embodiment of the present disclosure, there is also provided an electronic device, which may include a transceiver and one or more processors, which may be configured to perform the functions of the method or the corresponding units in the wireless communication system according to the embodiment of the present disclosure described above.

It should be understood that the machine-executable instructions in the storage media and program products according to the embodiments of the present disclosure may also be configured to perform methods corresponding to the above-described apparatus embodiments, and thus, contents not described in detail herein may refer to the description of the previous corresponding locations, and the description will not be repeated herein.

Accordingly, storage media for carrying the above-described program products comprising machine-executable instructions are also included in the present disclosure. Including, but not limited to, floppy disks, optical disks, magneto-optical disks, memory cards, memory sticks, and the like.

Further, it should be noted that the above series of processes and means may also be implemented by software and/or firmware. In the case of implementation by software and/or firmware, a program constituting the software is installed from a storage medium or a network to a computer having a dedicated hardware structure, such as a general-purpose personal computer 1700 shown in fig. 17, which is capable of executing various functions and the like when various programs are installed. Fig. 17 is a block diagram showing an example configuration of a personal computer as an information processing apparatus employable in the embodiments of the present disclosure.

In fig. 17, a Central Processing Unit (CPU)1701 executes various processes in accordance with a program stored in a Read Only Memory (ROM)1702 or a program loaded from a storage portion 1708 to a Random Access Memory (RAM) 1703. The RAM 1703 also stores data necessary when the CPU 1701 executes various processes and the like as necessary.

The CPU 1701, ROM 1702, and RAM 1703 are connected to each other via a bus 1704. An input/output interface 1705 is also connected to the bus 1704.

The following components are connected to the input/output interface 1705: an input section 1706 including a keyboard, a mouse, and the like; an output portion 1707 including a display such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker and the like; a storage portion 1708 including a hard disk and the like; and a communication section 1709 including a network interface card such as a LAN card, a modem, or the like. The communication section 1709 performs communication processing via a network such as the internet.

A driver 1710 is also connected to the input/output interface 1705 as necessary. A removable medium 1711 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 1710 as necessary, so that a computer program read out therefrom is installed in the storage portion 1708 as necessary.

In the case where the above-described series of processes is realized by software, a program constituting the software is installed from a network such as the internet or a storage medium such as the removable medium 1711.

It should be understood by those skilled in the art that such a storage medium is not limited to the removable medium 1711 shown in fig. 17 in which the program is stored, distributed separately from the apparatus to provide the program to the user. Examples of the removable medium 1711 include a magnetic disk (including a floppy disk (registered trademark)), an optical disk (including a compact disc read only memory (CD-ROM) and a Digital Versatile Disc (DVD)), a magneto-optical disk (including a Mini Disk (MD) (registered trademark)), and a semiconductor memory. Alternatively, the storage medium may be the ROM 1702, a hard disk included in the storage portion 1708, or the like, in which programs are stored and which are distributed to users together with the device including them.

Application examples according to the present disclosure will be described below with reference to fig. 18 to 21.

[ application example with respect to base station ]

(first application example)

Fig. 18 is a block diagram illustrating a first example of a schematic configuration of an eNB to which the technology of the present disclosure may be applied. The eNB 1800 includes one or more antennas 1810 and base station equipment 1820. The base station device 1820 and each antenna 1810 may be connected to each other via an RF cable.

Each of the antennas 1810 includes a single or multiple antenna elements, such as multiple antenna elements included in a multiple-input multiple-output (MIMO) antenna, and is used for the base station apparatus 1820 to transmit and receive wireless signals. As shown in fig. 18, the eNB 1800 may include multiple antennas 1810. For example, the multiple antennas 1810 may be compatible with multiple frequency bands used by the eNB 1800. Although fig. 18 shows an example in which the eNB 1800 includes multiple antennas 1810, the eNB 1800 may also include a single antenna 1810.

The base station device 1820 includes a controller 1821, memory 1822, a network interface 1823, and a wireless communication interface 1825.

The controller 1821 may be, for example, a CPU or a DSP, and operates various functions of higher layers of the base station apparatus 1820. For example, the controller 1821 generates data packets from data in signals processed by the wireless communication interface 1825 and communicates the generated packets via the network interface 1823. The controller 1821 may bundle data from the plurality of baseband processors to generate a bundle packet, and communicate the generated bundle packet. The controller 1821 may have logic functions to perform the following controls: such as radio resource control, radio bearer control, mobility management, admission control and scheduling. The control may be performed in connection with a nearby eNB or core network node. The memory 1822 includes a RAM and a ROM, and stores programs executed by the controller 1821 and various types of control data (such as a terminal list, transmission power data, and scheduling data).

The network interface 1823 is a communication interface for connecting the base station apparatus 1820 to the core network 1824. The controller 1821 may communicate with a core network node or another eNB via a network interface 1823. In this case, the eNB 1800 and a core network node or other enbs may be connected to each other through a logical interface, such as an S1 interface and an X2 interface. The network interface 1823 may also be a wired communication interface or a wireless communication interface for a wireless backhaul. If network interface 1823 is a wireless communication interface, network interface 1823 may use a higher frequency band for wireless communication than the frequency band used by wireless communication interface 1825.

The wireless communication interface 1825 supports any cellular communication scheme, such as Long Term Evolution (LTE) and LTE-advanced, and provides wireless connectivity via an antenna 1810 to terminals located in the cell of the eNB 1800. The wireless communication interface 1825 may generally include, for example, a baseband (BB) processor 1826 and RF circuitry 1827. The BB processor 1826 may perform various types of signal processing of layers such as L1, Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Protocol (PDCP), for example, encoding/decoding, modulation/demodulation, and multiplexing/demultiplexing. The BB processor 1826 may have a part or all of the above-described logic functions in place of the controller 1821. The BB processor 1826 may be a memory storing a communication control program, or a module comprising a processor and associated circuitry configured to execute a program. The update program may cause the function of the BB processor 1826 to change. The module may be a card or blade that is inserted into a slot of the base station device 1820. Alternatively, the module may be a chip mounted on a card or blade. Meanwhile, the RF circuit 1827 may include, for example, a mixer, a filter, and an amplifier, and transmit and receive a wireless signal via the antenna 1810.

As shown in fig. 18, wireless communication interface 1825 may include a plurality of BB processors 1826. For example, the plurality of BB processors 1826 may be compatible with the plurality of frequency bands used by the eNB 1800. As shown in fig. 18, wireless communication interface 1825 may include a plurality of RF circuits 1827. For example, the plurality of RF circuits 1827 may be compatible with a plurality of antenna elements. Although fig. 18 shows an example in which the wireless communication interface 1825 includes a plurality of BB processors 1826 and a plurality of RF circuits 1827, the wireless communication interface 1825 may also include a single BB processor 1826 or a single RF circuit 1827.

(second application example)

Fig. 19 is a block diagram illustrating a second example of a schematic configuration of an eNB to which the technology of the present disclosure may be applied. eNB1930 includes one or more antennas 1940, base station apparatus 1950, and RRHs 1960. The RRH 1960 and each antenna 1940 may be connected to each other via an RF cable. The base station apparatus 1950 and RRH 1960 may be connected to each other via a high-speed line such as a fiber optic cable.

Each of the antennas 1940 includes a single or multiple antenna elements (such as multiple antenna elements included in a MIMO antenna) and is used for the RRH 1960 to transmit and receive wireless signals. As shown in fig. 19, eNB1930 may include multiple antennas 1940. For example, the plurality of antennas 1940 may be compatible with a plurality of frequency bands used by eNB 1930. Although fig. 19 shows an example in which eNB1930 includes multiple antennas 1940, eNB1930 may also include a single antenna 1940.

The base station device 1950 includes a controller 1951, a memory 1952, a network interface 1953, a wireless communication interface 1955, and a connection interface 1957. The controller 1951, memory 1952, and network interface 1953 are the same as the controller 1821, memory 1822, and network interface 1823 described with reference to fig. 18. The network interface 1953 is a communication interface for connecting the base station device 1950 to a core network 1954.

Wireless communication interface 1955 supports any cellular communication scheme (such as LTE and LTE-advanced) and provides wireless communication via RRH 1960 and antenna 1940 to terminals located in a sector corresponding to RRH 1960. Wireless communication interface 1955 may generally include a BB processor 1956, for example. The BB processor 1956 is the same as the BB processor 1826 described with reference to fig. 18, except that the BB processor 1956 is connected to the RF circuitry 1964 of the RRH 1960 via a connection interface 1957. As shown in fig. 19, wireless communication interface 1955 may include a plurality of BB processors 1956. For example, the plurality of BB processors 1956 may be compatible with the plurality of frequency bands used by eNB 1930. Although fig. 19 shows an example in which the wireless communication interface 1955 includes a plurality of BB processors 1956, the wireless communication interface 1955 may include a single BB processor 1956.

Connection interface 1957 is an interface used to connect base station device 1950 (wireless communication interface 1955) to RRHs 1960. The connection interface 1957 may also be a communication module for communication in the above-described high speed lines connecting the base station device 1950 (wireless communication interface 1955) to the RRH 1960.

RRH 1960 includes connection interface 1961 and wireless communication interface 1963.

Connection interface 1961 is an interface for connecting RRH 1960 (wireless communication interface 1963) to base station apparatus 1950. The connection interface 1961 may also be a communication module for communication in the above-described high-speed line.

Wireless communication interface 1963 transmits and receives wireless signals via antenna 1940. Wireless communication interface 1963 may generally include, for example, RF circuitry 1964. The RF circuit 1964 may include, for example, mixers, filters, and amplifiers, and transmits and receives wireless signals via the antenna 1940. As shown in fig. 19, wireless communication interface 1963 may include a plurality of RF circuits 1964. For example, multiple RF circuits 1964 may support multiple antenna elements. Although fig. 19 shows an example in which wireless communication interface 1963 includes multiple RF circuits 1964, wireless communication interface 1963 may also include a single RF circuit 1964.

In the eNB 1800 and the eNB1930 shown in fig. 18 and 19, the transmitting unit in the

apparatuses

200 and 1000 may be implemented by the wireless communication interface 1825 and the wireless communication interface 1955 and/or the wireless communication interface 1963. At least a portion of the functions of the overlay control unit, the insertion control unit, and the indication generation unit may also be implemented by the controller 1821 and the controller 1951.

[ application example with respect to user Equipment ]

(first application example)

Fig. 20 is a block diagram showing an example of a schematic configuration of a smartphone 2000 to which the technique of the present disclosure can be applied. The smartphone 2000 includes a processor 2001, a memory 2002, a storage device 2003, an external connection interface 2004, a camera device 2006, sensors 2007, a microphone 2008, an input device 2009, a display device 2010, a speaker 2011, a wireless communication interface 2012, one or more antenna switches 2015, one or more antennas 2016, a bus 2017, a battery 2018, and an auxiliary controller 2019.

The processor 2001 may be, for example, a CPU or a system on a chip (SoC), and controls functions of an application layer and another layer of the smartphone 2000. The memory 2002 includes a RAM and a ROM, and stores data and programs executed by the processor 2001. The storage device 2003 may include a storage medium such as a semiconductor memory and a hard disk. The external connection interface 2004 is an interface for connecting an external device such as a memory card and a Universal Serial Bus (USB) device to the smartphone 2000.

The image pickup device 2006 includes an image sensor such as a Charge Coupled Device (CCD) and a Complementary Metal Oxide Semiconductor (CMOS), and generates a captured image. The sensors 2007 may include a set of sensors such as a measurement sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor. The microphone 2008 converts sound input to the smartphone 2000 into an audio signal. The input device 2009 includes, for example, a touch sensor, a keypad, a keyboard, a button, or a switch configured to detect a touch on the screen of the display device 2010, and receives an operation or information input from a user. The display device 2010 includes a screen, such as a Liquid Crystal Display (LCD) and an Organic Light Emitting Diode (OLED) display, and displays an output image of the smartphone 2000. The speaker 2011 converts an audio signal output from the smartphone 2000 into sound.

The wireless communication interface 2012 supports any cellular communication scheme (such as LTE and LTE-advanced) and performs wireless communication. The wireless communication interface 2012 may generally include, for example, a BB processor 2013 and RF circuitry 2014. The BB processor 2013 can perform, for example, encoding/decoding, modulation/demodulation, and multiplexing/demultiplexing, and perform various types of signal processing for wireless communication. Meanwhile, the RF circuit 2014 may include, for example, a mixer, a filter, and an amplifier, and transmit and receive a wireless signal via the antenna 2016. The wireless communication interface 2012 may be a chip module on which the BB processor 2013 and the RF circuit 2014 are integrated. As shown in fig. 20, the wireless communication interface 2012 may include a plurality of BB processors 2013 and a plurality of RF circuits 2014. Although fig. 20 shows an example in which the wireless communication interface 2012 includes multiple BB processors 2013 and multiple RF circuits 2014, the wireless communication interface 2012 may also include a single BB processor 2013 or a single RF circuit 2014.

Further, the wireless communication interface 2012 may support another type of wireless communication scheme, such as a short-range wireless communication scheme, a near field communication scheme, and a wireless Local Area Network (LAN) scheme, in addition to the cellular communication scheme. In this case, the wireless communication interface 2012 may include the BB processor 2013 and the RF circuit 2014 for each wireless communication scheme.

Each of the antenna switches 2015 switches the connection destination of the antenna 2016 among a plurality of circuits (e.g., circuits for different wireless communication schemes) included in the wireless communication interface 2012.

Each of the antennas 2016 includes a single or multiple antenna elements (such as multiple antenna elements included in a MIMO antenna) and is used for transmitting and receiving wireless signals by the wireless communication interface 2012. As shown in fig. 20, the smartphone 2000 may include multiple antennas 2016. Although fig. 20 shows an example in which the smartphone 2000 includes multiple antennas 2016, the smartphone 2000 may also include a single antenna 2016.

Further, the smartphone 2000 may include an antenna 2016 for each wireless communication scheme. In this case, the antenna switch 2015 may be omitted from the configuration of the smartphone 2000.

The bus 2017 connects the processor 2001, the memory 2002, the storage device 2003, the external connection interface 2004, the image pickup device 2006, the sensor 2007, the microphone 2008, the input device 2009, the display device 2010, the speaker 2011, the wireless communication interface 2012, and the auxiliary controller 2019 to each other. The battery 2018 provides power to the various blocks of the smartphone 2000 shown in fig. 20 via a feed line, which is partially shown in the figure as a dashed line. The supplementary controller 2019 operates the minimum necessary functions of the smartphone 2000 in, for example, a sleep mode.

In the smartphone 2000 shown in fig. 20, the receiving unit in the apparatuses 600 to 800 and 1100 may be implemented by the wireless communication interface 2012. At least a part of the functions of the equivalent channel estimation unit, the data demodulation unit, the power allocation coefficient determination unit, and the demodulation order determination unit may also be realized by the processor 2001 or the auxiliary controller 2019.

(second application example)

Fig. 21 is a block diagram showing an example of a schematic configuration of a car navigation device 2120 to which the technique of the present disclosure can be applied. Car navigation device 2120 includes a processor 2121, memory 2122, a Global Positioning System (GPS) module 2124, sensors 2125, a data interface 2126, a content player 2127, a storage medium interface 2128, an input device 2129, a display device 2130, speakers 2131, a wireless communication interface 2133, one or more antenna switches 2136, one or more antennas 2137, and a battery 2138.

The processor 2121 may be, for example, a CPU or an SoC, and controls a navigation function and another function of the car navigation device 2120. The memory 2122 includes a RAM and a ROM, and stores data and programs executed by the processor 2121.

The GPS module 2124 measures the position (such as latitude, longitude, and altitude) of the car navigation device 2120 using GPS signals received from GPS satellites. The sensors 2125 may include a set of sensors, such as a gyro sensor, a geomagnetic sensor, and an air pressure sensor. The data interface 2126 is connected to, for example, the in-vehicle network 2141 via a terminal not shown, and acquires data generated by the vehicle (such as vehicle speed data).

The content player 2127 reproduces content stored in a storage medium (such as a CD and a DVD) inserted into the storage medium interface 2128. The input device 2129 includes, for example, a touch sensor, a button, or a switch configured to detect a touch on the screen of the display device 2130, and receives an operation or information input from a user. The display device 2130 includes a screen such as an LCD or OLED display, and displays an image of a navigation function or reproduced content. The speaker 2131 outputs the sound of the navigation function or the reproduced content.

The wireless communication interface 2133 supports any cellular communication schemes (such as LTE and LTE-advanced) and performs wireless communication. The wireless communication interface 2133 may generally include, for example, a BB processor 2134 and RF circuitry 2135. The BB processor 2134 may perform, for example, encoding/decoding, modulation/demodulation, and multiplexing/demultiplexing, and perform various types of signal processing for wireless communication. Meanwhile, the RF circuit 2135 may include, for example, a mixer, a filter, and an amplifier, and transmits and receives a wireless signal via the antenna 2137. The wireless communication interface 2133 may also be one chip module on which the BB processor 2134 and the RF circuit 2135 are integrated. As shown in fig. 21, the wireless communication interface 2133 may include a plurality of BB processors 2134 and a plurality of RF circuits 2135. Although fig. 21 shows an example in which the wireless communication interface 2133 includes a plurality of BB processors 2134 and a plurality of RF circuits 2135, the wireless communication interface 2133 may also include a single BB processor 2134 or a single RF circuit 2135.

Further, the wireless communication interface 2133 may support another type of wireless communication scheme, such as a short-range wireless communication scheme, a near field communication scheme, and a wireless LAN scheme, in addition to the cellular communication scheme. In this case, the wireless communication interface 2133 may include a BB processor 2134 and RF circuitry 2135 for each wireless communication scheme.

Each of the antenna switches 2136 switches a connection destination of the antenna 2137 among a plurality of circuits (such as circuits for different wireless communication schemes) included in the wireless communication interface 2133.

Each of the antennas 2137 includes a single or multiple antenna elements (such as multiple antenna elements included in a MIMO antenna), and is used for the wireless communication interface 2133 to transmit and receive wireless signals. As shown in fig. 21, the car navigation device 2120 may include a plurality of antennas 2137. Although fig. 21 shows an example in which the car navigation device 2120 includes the plurality of antennas 2137, the car navigation device 2120 may include a single antenna 2137.

Further, the car navigation device 2120 may include an antenna 2137 for each wireless communication scheme. In this case, the antenna switch 2136 may be omitted from the configuration of the car navigation device 2120.

The battery 2138 supplies power to the respective blocks of the car navigation device 2120 shown in fig. 21 via a feeder line, which is partially shown as a broken line in the drawing. The battery 2138 accumulates electric power supplied from the vehicle.

In the car navigation device 2120 shown in fig. 21, the receiving unit in the apparatuses 600 to 800 and 1100 may be implemented by the wireless communication interface 2133. At least a part of the functions of the equivalent channel estimation unit, the data demodulation unit, the power allocation coefficient determination unit, and the demodulation order determination unit may also be implemented by the processor 2121.

The techniques of this disclosure may also be implemented as an in-vehicle system (or vehicle) 2140 that includes one or more blocks of a car navigation device 2120, an in-vehicle network 2141, and a vehicle module 2142. The vehicle module 2142 generates vehicle data (such as vehicle speed, engine speed, and fault information) and outputs the generated data to the on-board network 2141.

The preferred embodiments of the present disclosure are described above with reference to the drawings, but the present disclosure is of course not limited to the above examples. Various changes and modifications within the scope of the appended claims may be made by those skilled in the art, and it should be understood that these changes and modifications naturally will fall within the technical scope of the present disclosure.

For example, a plurality of functions included in one unit may be implemented by separate devices in the above embodiments. Alternatively, a plurality of functions implemented by a plurality of units in the above embodiments may be implemented by separate devices, respectively. In addition, one of the above functions may be implemented by a plurality of units. Needless to say, such a configuration is included in the technical scope of the present disclosure.

In this specification, the steps described in the flowcharts include not only the processing performed in time series in the described order but also the processing performed in parallel or individually without necessarily being performed in time series. Further, even in the steps processed in time series, needless to say, the order can be changed as appropriate.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Also, the terms "comprises," "comprising," or any other variation thereof, of the embodiments of the present disclosure are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims

1. An apparatus on a base station side in a wireless communication system for multi-user superposition transmission, the apparatus comprising:

a superposition control unit configured to insert a demodulation reference signal corresponding to a data stream in each data stream of a group of user equipments including a plurality of user equipments and superpose the demodulation reference signals corresponding to the data streams of the user equipments, wherein the superposition control unit allocates a specific transmission power to the data stream of the user equipments so that the data stream of the user equipments is transmitted to the user equipments with the same time-frequency resources without using mimo performance gain and/or code division multiplexing; and

an indication generating unit configured to generate, for at least a first user equipment of the plurality of user equipments, an indication of demodulation reference signals corresponding to data streams of other user equipments of the plurality of user equipments to assist the first user equipment in demodulating data of multi-user superposition transmission,

wherein the superposition control unit is further configured to determine a reference signal group for the group of user equipments from a plurality of reference signal groups respectively composed of a plurality of demodulation reference signals, wherein the determined reference signal group contains a number of demodulation reference signals greater than or equal to a number of user equipments contained in the group of user equipments, and the indication contains an index with respect to the determined reference signal group.

2. The apparatus of claim 1, wherein the demodulation reference signals corresponding to the data streams of the respective user equipments have different orthogonal codes such that the demodulation reference signals corresponding to the data streams of the respective user equipments are transmitted to the respective user equipments on a same resource element.

3. The apparatus of claim 2, wherein each user equipment has only a single-layer data stream, and the superposition control unit inserts demodulation reference signals supporting only the single-layer data stream into the data streams of the respective user equipments, respectively.

4. The apparatus of claim 1, wherein the superposition control unit is further configured to allocate a specific transmission power to demodulation reference signals corresponding to data streams of the respective user equipments and superpose the demodulation reference signals corresponding to the data streams of the respective user equipments according to the allocated power, and wherein a superposition manner of the demodulation reference signals corresponding to the data streams of the respective user equipments is different from a superposition manner of the data streams of the respective user equipments.

5. The apparatus of claim 1, wherein the superposition control unit is further configured to assign a specific transmit power to demodulation reference signals corresponding to data streams of the respective user equipments and superpose the demodulation reference signals corresponding to the data streams of the respective user equipments according to the assigned power, and wherein the transmit power assigned to the demodulation reference signals corresponding to the data streams of the respective user equipments is the same as the transmit power assigned to the data streams.

6. The apparatus of claim 1, wherein the indication is included in physical layer signaling.

7. The apparatus of claim 1, wherein the indication further includes information of demodulation reference signals for the first user equipment in the determined set of reference signals.

8. The apparatus of claim 1, wherein the indication further comprises at least one bit for indicating to a user equipment an indication manner regarding demodulation reference signals, the indication manner comprising a demodulation reference signal group indication manner and a legacy demodulation reference signal indication manner.

9. The apparatus of claim 8, wherein the indication generating unit is further configured to use a legacy demodulation reference signal indication scheme for at least a second user equipment in the set of user equipments.

10. The apparatus of claim 1, further comprising: a storage unit configured to store information of a demodulation reference signal group set including the plurality of reference signal groups, wherein a plurality of demodulation reference signals included in each demodulation reference signal group are code-division orthogonal to each other, the superposition control unit reading the storage unit to determine a reference signal group for the group of user equipments.

11. The apparatus of any of claims 1-10, wherein the apparatus is the base station, and the apparatus further comprises:

a transmitting unit configured to transmit the superimposed demodulation reference signal and the indication to at least the first user equipment.

12. An apparatus on a user equipment side in a wireless communication system for multi-user superposition transmission, the apparatus comprising:

an equivalent channel estimation unit configured to estimate an equivalent channel corresponding to a data stream of the user equipment and an equivalent channel corresponding to a data stream of other user equipment according to an indication from a base station about a demodulation reference signal of the user equipment and a demodulation reference signal of the other user equipment after superposition, wherein the demodulation reference signal of the user equipment and the demodulation reference signal of the other user equipment are respectively inserted into the data streams of the user equipments, and the data streams of the user equipments are transmitted by the base station at a specific transmission power and with the same time-frequency resources without utilizing multiple-input multiple-output performance gain and/or code division multiplexing; and

a data demodulation unit configured to demodulate data of the multi-user superposition transmission according to the estimated equivalent channel,

wherein the equivalent channel estimation unit is further configured to determine, from the indication, an index of a reference signal group for a group of user equipments including the user equipment and the other user equipments, wherein a number of demodulation reference signals in the reference signal group is greater than or equal to a number of user equipments in the group of user equipments.

13. The apparatus of claim 12, wherein the demodulation reference signals for the respective user equipments have different orthogonal codes such that the demodulation reference signals for the respective user equipments are transmitted to the respective user equipments on a same resource element.

14. The apparatus of claim 13, wherein each user equipment has only a single-layer data stream, and demodulation reference signals supporting only the single-layer data stream are inserted into the data stream of each user equipment.

15. The apparatus of claim 12, wherein the demodulation reference signals for the respective user equipments are assigned a specific transmit power and the superimposed demodulation reference signals are superimposed according to the assigned transmit power, and wherein a manner of superimposing the demodulation reference signals for the respective user equipments is different from a manner of superimposing the data streams of the respective user equipments.

16. The apparatus of claim 12, wherein demodulation reference signals for respective user equipments are assigned a specific transmit power and the superimposed demodulation reference signals are superimposed according to the assigned transmit power, and wherein the transmit power assigned to the demodulation reference signals for respective user equipments is the same as the transmit power assigned to the data streams of the user equipments.

17. The apparatus of claim 12, wherein the equivalent channel estimation unit is further configured to obtain the indication from physical layer signaling from the base station.

18. The apparatus of claim 12, further comprising:

a power distribution coefficient determination unit configured to determine power distribution coefficients of the user equipment and the other user equipments according to the estimated equivalent channel,

wherein the data demodulation unit is further configured to demodulate data of the multi-user superposition transmission according to the determined power distribution coefficient.

19. The apparatus of claim 18, wherein the data demodulation unit is further configured to recover a constellation diagram for demodulating data of a multi-user superposition transmission according to the determined power allocation coefficients.

20. The apparatus of claim 12, further comprising:

a demodulation order determination unit configured to determine a data demodulation order of the user equipment and the other user equipments according to the estimated equivalent channel,

wherein the data demodulation unit is further configured to demodulate the data of the multi-user superposition transmission according to the determined data demodulation order.

21. The apparatus of claim 20, wherein the data demodulation unit is further configured to demodulate the data of the multi-user superposition transmission in a non-linear interference cancellation manner according to the determined data demodulation order.

22. The apparatus of claim 12, wherein the equivalent channel estimation unit is further configured to determine demodulation reference signals for the other user equipments according to the index and information on demodulation reference signals for the user equipments contained in the indication, and the data demodulation unit demodulates data of multi-user superposition transmission according to the determined demodulation reference signals.

23. The apparatus of claim 12, wherein the equivalent channel estimation unit is further configured to determine an indication manner of the demodulation reference signal of the user equipment according to the indication, the indication manner comprising a demodulation reference signal group indication manner and a legacy demodulation reference signal indication manner.

24. The apparatus of claim 23, wherein the manner in which the demodulation reference signal of at least one of the set of user equipments is indicated is the legacy demodulation reference signal indication manner.

25. The apparatus according to any one of claims 12 to 24, wherein the apparatus is the user equipment, and the apparatus further comprises:

a receiving unit configured to receive the superimposed demodulation reference signal and the indication from the base station.

26. A method at a base station side in a wireless communication system for multi-user superposition transmission, the method comprising:

inserting a demodulation reference signal corresponding to a data stream into the data stream of each user equipment in a group of user equipment comprising a plurality of user equipments respectively and superposing the demodulation reference signals corresponding to the data streams of the user equipments, wherein the data streams of the user equipments are allocated with specific transmission power so that the data streams of the user equipments are transmitted to the user equipments with the same time-frequency resources without utilizing MIMO performance gain and/or code division multiplexing; and

generating, for at least a first user equipment of the plurality of user equipments, an indication of demodulation reference signals corresponding to data streams of other user equipments of the plurality of user equipments to assist the first user equipment in demodulating data of a multi-user superposition transmission,

wherein the method further comprises: determining a reference signal group for the group of user equipments from a plurality of reference signal groups respectively composed of a plurality of demodulation reference signals, wherein the determined reference signal group contains a number of demodulation reference signals greater than or equal to a number of user equipments contained by the group of user equipments, and the indication contains an index with respect to the determined reference signal group.

27. A method at a user equipment side in a wireless communication system for multi-user superposition transmission, the method comprising:

estimating equivalent channels corresponding to data streams of the user equipment and equivalent channels corresponding to data streams of other user equipment according to indications of the demodulation reference signals of the user equipment and other user equipment after superposition and the demodulation reference signals of the other user equipment from a base station, wherein the demodulation reference signals of the user equipment and the demodulation reference signals of the other user equipment are respectively inserted into the data streams of the user equipment, and the data streams of the user equipment are transmitted by the base station at specific transmission power and same time-frequency resources without utilizing multi-input multi-output performance gain and/or code division multiplexing; and

demodulating data of the multi-user superposition transmission according to the estimated equivalent channel,

wherein the method further comprises: determining an index of a reference signal group for a group of user equipments including the user equipment and the other user equipments according to the indication, wherein a number of demodulation reference signals in the reference signal group is greater than or equal to a number of user equipments in the group of user equipments.